Glossary

This glossary includes terms likely to be encountered in descriptions and identification keys to Flowering Plants. Some of the words listed have more than one meaning in biology but only the botanical usage is given here. Many terms are used as nouns as well as adjectives; both forms are listed if commonly used. The adjective is often derived from the noun by the addition of ‘ate’.

Current botanical terminology, composed of contributions by numerous authors over several hundred years, includes some groups of terms for which strict definitions seem at present unattainable. Examples include terms for some leaf shapes, some fruit types and for a few inflorescence types. In some cases an individual term may be applied to more than one structure or, conversely, a particular structure might be referred to by a number of different terms. Sometimes definitions of terms vary between authors. At times the terminology used in floras accepts a certain degree of latitude with respect to definitions. Sometimes the resulting imprecision is useful in matching the variability of nature, and is scarcely a liability. In other cases it becomes a matter of the reader understanding and working with the meanings as they are applied in a particular text.

With respect to inflorescences, a few relatively recent terms (now quite common in the specialist literature) are included here on the assumption that they may find their way into general identification sources in the future.

Online glossaries include: Flora of North America North of Mexico: www.huntbotanical.org/databases/show.php?4

Flora of Australia:

155.187.2.69/biodiversity/abrs/online-resources/glossaries/vascular/index.html A study of fruit types is at http://www.worldbotanical.com/fruit_types.htm

abaxial   of orientation, facing away from the axis, e.g. the surface of an organ (often a leaf or bract) facing away from the axis to which it is joined. Cf. adaxial. Referring to the orientation of a grass spikelet, having the lower glume (and therefore lower floret) on the side away from the axis.

abbreviated   shortened, e.g. an axis.

abort   fail to develop, e.g. ovules that fail to develop into seeds.

abscission   the shedding or detaching, e.g. of leaves, fruits, bark etc., at a predetermined point or zone by the laying down of a special layer of cells.

acaulescent   of a plant, stemless or apparently so.

accrescent   of parts that increase in size as they age, e.g. a calyx that grows to enclose the developing fruit (e.g. Pl. 30i).

achene   a fruit type; a term rather inconsistently applied, but often and usefully defined as a dry, indehiscent, one-seeded fruit, produced from the superior ovary of a single carpel, in which the seed is free from the rather thin or leathery pericarp. A typical example is the fruit of the individual carpels within the flowers of Ranunculus (Buttercup) or Clematis. Sometimes also applied to a one-seeded fruit from an inferior ovary and/or not necessarily from one carpel. An example is the fruit of each floret in the Daisy Family (these mostly called cypselas). It may be further specified that the pericarp is thin and/or is contiguous with the seed. When not defined as the product of one carpel, the achene is then sometimes distinguished from the nut (q.v.) on the basis of a softer, thinner pericarp. Occasionally used to refer to certain grass fruits (e.g. Sporobolus), but these are alternatively considered to be caryopses that have become achene-like due to collapse of the inner layer(s) of the pericarp.

acicular   needle-shaped.

acropetal   of development of a series of structures, progressing towards the apex, e.g. of flowers in an inflorescence.

acrotonic   of an inflorescence in which lateral flowers or branches are mainly concentrated towards the apex. Of a branching system generally in which the lateral branches are mainly (or better) developed in the upper part (cf. basitonic).

actinomorphic   of a flower from above, radially symmetrical, resulting in many planes of symmetry (e.g. Fig. 2a–c). Also regular. Cf. zygomorphic.

acuminate   of an apex, with the margins curving gradually (bowed in towards the midline) and narrowing to a point (Fig. 17).

aculeate   usually of branches or branchlets, provided with prickles.

acute   in general, with two edges/margins meeting at a narrow angle (< 90°); of an apex, coming to a fine, rather abrupt point (Fig. 17).

adaxial   of orientation, facing the axis, e.g. the surface of an organ (often a leaf or bract) facing the axis to which it is joined. Cf. abaxial. With reference to a grass spikelet, with the lower glume (and therefore lower floret) on the side adjacent to the axis.

addorsed   of a prophyll, an adaxial prophyll, i.e. positioned on the adaxial side (adjacent to the axis) of an axillary shoot.

adherent   with unlike parts or organs joined but only superficially, and without tissue continuity.

adnate   with unlike or like parts or organs integrally fused to one another with continuity of tissues.

adventitious   of tissues or organs developing in an ‘abnormal’ position, e.g. adventitious roots arising from lower stems (Fig. 120).

adventive (noun or adj.)   a plant or species introduced and growing wild in an area, i.e. not native. Sometimes also thought of as not (yet) naturalised.

aerenchyma   a type of cellular tissue with large air spaces between the rather thin-walled cells, e.g. in culms and leaves. Common in aquatic plants. Adj. aerenchymatous.

aestivation   the arrangement of flower parts in the bud, particularly of the sepals and petals.

aggregate fruit   a category of fruit types in which each fruit is the product of all the individual mature free carpels in one flower. The individual ‘fruitlets’ may be fleshy as in blackberries, or dry as in buttercups.

alate   winged. Any structure (fruit, petiole, stem etc.) is said to be winged when bearing one or more thin, flat, flange-like extensions of tissue projecting beyond a ‘normal’ margin.

alien   a plant or species growing in a particular region but not native there, having been introduced by some means from its natural range.

allopatric   of species or other taxa, occurring in different geographic areas, i.e. their distributions do not overlap. Cf. sympatric.

alternate   of leaves that arise singly at the nodes, thus each leaf appearing at a different level on the axis (Fig. 15).

alveolae/alveoli (plur.)   in general, small cavities or depressions on a surface, sometimes regularly patterned e.g. as in honeycomb.

amphicarpic   of a plant or species, possessing two kinds of inflorescence (and thus producing two kinds of fruits), one often at the base of a culm and the other aerial. The fruits may differ in size, shape, ornamentation, time of ripening etc.

amphipodial   of a rhizome system when exhibiting both monopodial and sympodial branching (as apparently in some bamboos).

amphistomous   of a leaf, bearing stomata on both surfaces. Cf. epistomous, hypostomous.

amplexicaul   stem clasping, e.g. of the base of a sessile leaf when it extends around each side of the stem.

anastamose   linking up to form a network, e.g. the veins of a bract or leaf etc.

androecium   the stamens of a flower collectively (Fig. 1), almost universally taken to be the ‘male’ part of the flower. (The term ‘male’ more correctly applies to that part of each pollen grain made up of cells that have undergone cell division in which the chromosome number is halved. These cells are thus haploid.)

androdioecious   of a species in which some plants bear male flowers and others bear bisexual flowers.

androgynophore   within a flower, a stalk raising the stamens and carpels above the level of attachment of the perianth (Pl. 22d).

androgynous   in general, of a plant having male and female flowers in the same inflorescence. Of bisexual spikes in some Carex inflorescences, when the male flowers are above the female within each spike. Cf. gynecandrous.

andromonoecious   of a plant or a species, in which plants bear both male and bisexual flowers.

anemophilous   of a plant or a species, wind pollinated.

Angiosperms   a major subgroup of the plant kingdom—the Flowering Plants. Formally spelled Angiospermae.

annual   (noun or adj.) a plant that completes its life cycle in one growing season.

anterior   of orientation, in general, towards the front; of a flower, the side away from the axis.

anthecium/anthoecium   used variously by authors for the floral unit or the fruiting unit of grasses, consisting of the flower/caryopsis plus lemma and palea, and also by some the rachilla. Other authors restrict its definition to just the floral envelope of lemma and palea, excluding the flower, or sometimes narrow it further to one-flowered spikelets with articulation above the glumes. Thus in some contexts the term could be synonymous with floret.

anthela   a branched inflorescence type in which the lateral branches exceed and overtop the parent axis. Commonly applied to members of the Juncaceae (Rush Family) and Cyperaceae (Sedge Family). Adj. anthelate.

anthelodium   an inflorescence type in general form similar to the anthela (q.v.) but restricted to apply to indeterminate inflorescences (and therefore according to some authors more appropriate to sedge inflorescences than anthela).

anther   the pollen-bearing part of a stamen (Figs. 1, 3).

anthesis   referring to flowers, the time of opening from the bud stage.

anthocarp   a general term for a ripened ovary with attached parts that have undergone development to aid dispersal. Examples include a caryopsis with surrounding bracts (as in many grasses), a cypsela with attached pappus (as in many daisies), the apple with its fleshy hypanthium, the strawberry with its swollen fleshy receptacle.

anthotelic   of an inflorescence, or part thereof, ending in a flower or floral bud Cf. blastotelic. See also determinate, monotelic.

antrorse   usually of hairs or surface projections, directed towards the apex of the organ bearing them. Cf retrorse.

apetalous   without petals.

aphyllopodic   a fertile stem that has bladeless leaf sheaths at the base (usually in reference to certain Carex species). Cf phyllopodic.

aphyllous   without leaves.

apical   pertaining to, or situated at, the apex or tip.

apiculate   ending in an abrupt short point (an apiculum), often at the apex.

apocarpous   of a gynoecium made up of free (separate) carpels (Fig. 1; Pl. 1).

apomictic   of reproduction which does not involve fertilisation. Thus includes the production of seed that has formed without fertilisation, as well as forms of vegetative reproduction.

apomorphy   a characteristic believed to be derived (i.e. to have evolved through time) from an ancestral condition, and now unique to a particular species or group (i.e. a defining feature). Adj. apomorphic, cf. plesiomorphy.

appendage   an external outgrowth, often having no obvious function.

appressed   closely flattened to.

approximate   of parts that are close together, not distant or remote, e.g. of lateral branches of an inflorescence when closely spaced.

aquatic   (noun or adj.) of plants, or other organisms, or species that live in water.

arachnoid   of hairs when rather loose, cottony and entangled; cobweb-like.

arborescent   tree-like in general appearance.

aril   a fleshy, often coloured, outgrowth from the seed coat or funicle, often (partially) enclosing the seed. Adj. arillate.

arista   a fine awn or bristle. Adj. aristate, bearing an arista, usually apically (Fig. 17).

articulate   in general, jointed. Of a leaf, having a distinct point of attachment to the stem from which it arises (Fig. 15, cf. decurrent). Of an inflorescence axis in some grasses that breaks up at the joints, e.g. Hordeum leporinum (Barleygrass), or inflorescence branch as in Sorghum. Cf. continuous.

articulation   in general, separation at a joint. Of grass spikelets, the mode of breaking apart, most often either above or below the glumes (Fig. 37), and in this context the term disarticulation is an alternative.

ascending   in general, growing or becoming more upright during growth, as in a stem that is initially more or less horizontal but later grows more upright.

asepalous   without sepals.

asexual   of reproduction that does not involve gametes (q.v.), i.e. vegetative reproduction.

attenuate   gradually narrowed or tapering, as in a leaf base (Fig. 17).

auricles   appendages or lobes. In some grasses and similar species usually at the base of the leaf blade or apex of the leaf sheath, occasionally elsewhere.

author(s)   of a botanical name (species or other rank), the person(s) who published the name according to the rules of botanical nomenclature.

authority   for a botanical name, the name(s) of the publishing author(s), most often seen in abbreviated form following the name of a species or other botanical group in scientific literature.

awn   a needle-like appendage or stiff bristle, e.g. in grasses often appearing as a continuation of the midvein of a lemma or glume. Sometimes with a lower column (often twisting in response to changes in humidity), and a terminal bristle. When incorporating a distinct knee-like bend, an awn may be referred to as geniculate.

axil   the angle between the upper (adaxial) surface of a leaf or bract and the stem to which it is attached. In cases such as the grasses where the leaves have a sheathing base, this effectively means the axil is within the sheath.

axile   of placentation, with ovules attached to placentas on the central axis within the loculi of the ovary (Fig. 5f; Pls. 11c, 28e).

axillary   pertaining to an axil, e.g. of buds or flowers arising in an axil.

axis (plur. axes)   in general, the central supporting member, e.g. of a whole plant, or of an inflorescence etc. Sometimes more conceptual as in the central longitudinal ‘core’ of an ovary of united carpels where the septa join.

baccate   of a fruit, fleshy or pulpy in nature; berry-like.

banner   in a pea flower, the (usually) large petal at the ‘back’ of the flower. See also standard.

barb   a small sharp projection, usually projecting backwards.

barbellate   minutely barbed.

bark   the protective external layer of tissue on the stems, branches and roots of shrubs and trees.

barren   infertile, not producing seed.

basal   pertaining to, situated or attached at, the base.

basifixed   of anthers, attached at the base to the filament (e.g. Figs. 3b, 42b; Pl. 1d).

basipetal   of development of a series of structures, progressing towards the base. Cf. acropetal.

basitonic   of an inflorescence, in which the lateral flowers or branches are mainly developed towards the base; of a branching system more generally, in which lateral branches are better developed towards the base. Cf. acrotonic.

beak   in general, an elongated (usually pointed) extension of, or appendage arising at, the apex of a structure, e.g. on a cypsela in the Daisy Family (Fig. 124c; Pl. 32k).

bearded   bearing rather long stiff hairs, or with such hairs in tufts over a relatively small area.

berry   a fruit type; an indehiscent fleshy fruit (the fleshy layer derived only from the ovary wall), often containing many seeds, e.g. tomato.

biconvex   of a two-sided structure (e.g. a leaf blade or fruit) in which each side is somewhat rounded or domed (convex), thus the structure is more or less elliptical in cross-section.

bidentate   bearing two teeth.

biennial   a plant that develops vegetatively in the first year and produces a food-storage organ such as a tap root, then flowers and dies off in the second year.

bifacial   having two distinct (usually upper and lower) surfaces, e.g. of leaves. Cf. unifacial.

bifid   usually of an apex, forked or divided into two parts.

bifoliolate   of a compound leaf, with two leaflets.

bilabiate   having two lips, e.g. of a calyx or corolla (Pl. 31c, j–m).

bilateral   with structures arranged on opposite sides of an axis.

bilobed   with two lobes.

binomial   (in nomenclature) the species name, composed of the generic name and specific epithet.

bipinnate   of a compound leaf, twice divided, i.e. with leaflets pinnately divided (Fig. 14e, j).

bipinnatisect   a pinnatisect leaf with deeply dissected segments (Fig. 18).

biserrate   referring to a serrate margin (e.g. of a leaf) when the individual teeth are themselves serrate (Fig. 18).

bisexual   of a flower, bearing both male and female sex organs (stamens and carpels); of a spikelet, bearing florets with both stamens and carpels; hermaphrodite.

blade   the lamina, or flattened part of a leaf, usually borne at the end of the petiole or sheath. Sometimes also used for the expanded part of a petal.

blastotelic   of an inflorescence axis or part of an inflorescence, when ending in a non-floral bud, i.e. not ending in a flower. Cf. anthotelic. See also indeterminate, indefinite.

body   of a grass lemma with apical lobes or awn(s), the part between the base of the lemma and the sinus between the apical lobes, or the base of the awn(s) (may or may not include the lemma callus depending on the author); of a grass palea, that part between the two keels.

bostryx   an inflorescence type, a compound monochasium in which the bracts and flowers are arranged in a spiral around the axis. Also helicoid cyme.

botrys/botryum   see raceme.

botryoid   see raceme.

brachyblast   a short shoot, sometimes called a spur shoot.

bract   a general term for a modified, often reduced or much-reduced, leaf (adj. bracteate, bracteose). Often applied to (usually small) leaf-like organs subtending inflorescence branches or flowers or buds (e.g. Fig. 10). A gemmiparous bract bears a bud in its axil. The terms bracteole, glume, lemma, spathe and spatheole could all be grouped under the general heading of bracts.

bracteole   a small bract-like organ, the term most often applied to those found on the pedicel or calyx of a flower (e.g. Figs. 63a, 68a; Pl. 28b). Thus arising from the uppermost node of the axis ending in the flower, and in this case usually not subtending further axillary growth. Usually single in Monocots and paired in ‘Dicots’. Under this definition, when a flower terminates a short shoot with no other nodes, the bracteole corresponds to a prophyll. The term is sometimes applied more generally.

branch complement   of bamboos, the cluster of branches arising from one (mid)culm node. The number of branches in the cluster may be characteristic of the species.

bristle   generally a stiff hair-like structure; sometimes part of an awn—the apical, usually straight section beyond a twisted column. Bristle is the English equivalent to the Latin seta, but the distinctions between these two terms, as well as stiff hair and spine are sometimes unclear.

bud   an undeveloped shoot, inflorescence or flower that may later grow out to maturity.

bulb   a short underground stem encased in fleshy leaf-bases that store food material, and enclose one or more buds for next season’s growth (Fig. 33a; Pl. 9a).

bulbil   a small bulb-like structure These are sometimes produced adventitiously in leaf axils, or within an inflorescence or spikelet etc., and may subsequently detach and give rise to a new plant. Adj. bulbiferous, producing bulbils.

bulbous   of a structure, swollen and resembling a bulb, e.g. a stem base; also bulb-forming, i.e. describing a plant that arises from a bulb.

bullate   of a surface, with raised blister-like swellings or puckers.

bulliform   bubble-like. Mostly seen in reference to certain cells forming part of the leaf epidermis of some grass and sedge species, and sometimes suggested to be involved in folding or rolling of the leaf blade.

bunchgrass   a description of habit, where upright aerial shoots arise in a tight cluster from a very short rhizome. More or less equivalent to a caespitose or tussocky grass habit.

bundle sheath   a cylinder of cells, made up of one or two rings of cells, surrounding a vascular bundle.

burr (bur)   a dispersal unit of certain Grasses, made up of one or more spikelets surrounded by spiny bracts or bristles; also used for fruits in other groups, e.g. the spiny coiled legumes of some species of Medicago.

buttress   a structure radiating from the base of a tree trunk merging down into a lateral root, and providing support (Pl. 17a), mostly seen in rainforest species.

caducous   non-persistent, falling early (often of floral parts).

caespitose (cespitose)   of growth habit, tufted and forming a more or less compact clump.

calli (plur.)   of orchid flowers, thickenings or more elongated outgrowths, often glandular, usually found on the labellum (Fig. 24b).

callus (sing.)   in general, a thickening, or thickened part; of some grasses, the hardened, usually pointed base of the lemma where it disarticulates from the rachilla, or of the spikelet where it disarticulates from the pedicel; of orchid flowers, a general thickening or thickened part, often on the labellum (Fig. 24b).

calyculus   in the flowerheads of Asteraceae (Daisy Family), one or more usually smaller bracts forming one or few series outside/at the base of the involucral bracts.

calyptra   usually of flowers or fruits, a cap or lid-like covering.

calyx (plur. calyces)   in a flower, the sepals collectively, in most cases the outermost whorl of floral parts (Fig. 1).

calyx tube   a tube formed by fusion of the sepals (Pl. 21b); used by some authors to refer to the floral tube (q.v.).

canaliculate   with a longitudinal groove or channel.

cancellate   having the appearance of a lattice.

capillary   very fine, hair-like.

capitate   bearing or resembling a head; head- or knob-shaped, e.g. of a stigma; also often used to describe a dense, head-like inflorescence.

capitulum (plur. capitula)   a compact group of sessile flowers on a very short and sometimes flattened or expanded axis, e.g. the inflorescence in most daisies. Also sometimes used to refer to any compact group of flowers. See also head.

capsule   a fruit type; a dry, dehiscent fruit developed from a syncarpous ovary (Figs. 81, 87c; Pls. 19j, 20a).

carinate   keeled, i.e. with a more or less sharp longitudinal fold or ridge, e.g. along the midline of a grass lemma or leaf blade.

carnose   fleshy.

carpel   the basic structural unit of the gynoecium, made up of an ovary (containing one or more ovules), style and stigma (Fig. 1; Pl. 1c).

carpophore   in general, the stalk of a fruit within the old flower, i.e. between the perianth and gynoecium.

carpodium (plur. carpodia)   in Typha (Bulrush) a modified, sterile gynoecium.

carpopodium   in general, a fruit stalk.

cartilaginous   cartilage-like, firm and rather tough but flexible.

caruncle   an outgrowth of the outer seed coat, e.g. in Luzula (Woodrush).

caryopsis   a dry, one-seeded, indehiscent fruit, derived from a superior ovary, with the thin pericarp closely adhering to the testa. This is the ‘typical’ fruit type of the Grass Family, most often shed with accompanying structures such as lemma and palea etc. The testa is fused to the pericarp in the region of the hilum.

castaneous   chestnut-brown coloured.

cataphyll   in general, a reduced leaf, often sheath- or scale-like, at the base of a shoot. May have a protective function around a bud, and be succeeded by normal leaves.

catkin   an inflorescence type; a pendulous spike usually with small, bracteate, unisexual flowers, e.g. in willows and birches.

caudate   tailed, bearing a tail-like appendage.

caudex   in general, a persistent stem of an herbaceous perennial, in some cases (partly) underground. Also applied to the stems of certain slow-growing, long-lived species such as some palms, cycads, and Xanthorrhoea spp. (Grass-tree).

caudicle   in orchid flowers, a stalk attaching the pollen mass to the rostellum.

cauline   in general, pertaining to the stem; of leaves, growing from the stem. Cf. radical, basal.

caulescent   of a plant, having an evident stem.

cell   the structural unit of organisms. Also sometimes used as a synonym for loculus (q.v.), as in ‘ovary 2-celled’ or ‘ovary 3-celled’.

cereal   a grass species providing grain for human or animal consumption, e.g. Barley, Maize, Oats, Wheat etc.

cespitose   see caespitose.

channelled   of a structure (e.g. a leaf), bearing a longitudinal furrow or groove. Equivalent to canaliculate.

chartaceous   papery, i.e. thin but with some stiffness.

chasmogamous   of flowers or florets that open normally for pollination. Cf. cleistogamous.

chlorenchyma   a tissue made up of cells containing the green pigment chlorophyll, involved in photosynthesis.

chlorophyll   a green pigment in chloroplasts, essential for the process of photosynthesis.

chloroplast   an organelle, present in plant cells, that contains chlorophyll.

ciliate   usually of a margin, bearing fine hairs (cilia) often forming a fringe (Fig. 17). Dim. ciliolate.

cincinnus   an inflorescence type, a compound monochasium in which each successive branch arises from the axil of a lateral bract such that the flowers form a zigzag pattern curving towards one side of the inflorescence. Equivalent to a scorpioid cyme.

circinate(circinnate)   of parts that unroll from the base upwards (e.g. the fronds of many ferns), the distal end appearing like a spiral.

circumcissile   of a fruit that breaks open around its circumference (the top then effectively like a lid or cap, e.g. Pl. 27j).

circumscription   of a taxon (species, genus, family etc), the breadth or range of characteristics contained within its description and which distinguish it from other taxa.

clade   in systematics, a monophyletic group (a general term, not restricted to any particular rank), hence cladogram (q.v.). Cf. grade.

cladode   a photosynthetic stem, often flattened, e.g. of certain cacti. Sometimes quite leaf-like, e.g. in Ruscus (Butcher’s Broom) or Asparagus (Pl. 11d).

cladogram   a diagrammatic representation of evolutionary relationships, summarising the links between ancestors and their descendants. Sometimes treelike in appearance, hence also ‘phylogenetic tree’.

cladoprophyll   within the inflorescences of certain Sedges, the prophyll found at the base of lateral branches (but see also inflorescence prophyll).

clavate   club-shaped. Dim. clavellate.

claw   a narrowed base, e.g. of a petal, sepal, bract etc. which has a broader blade.

cleft   of a margin, e.g. that of a leaf, when cut about halfway or more to the midvein into several pointed lobes. Inconsistently defined, roughly equivalent to incised (q.v.).

cleistogamous   of flowers or florets that do not open, self-fertilisation taking place within. Cf. chasmogamous.

cleistogene   in some grasses, a modified spikelet, containing self-compatible floret(s), these usually hidden within basal sheaths or produced at the culm nodes.

coalescent   partially or incompletely fused, more or less irregularly.

cob   the female inflorescence of Zea (Maize, Corn), especially in the fruiting stage.

coccus (plur. cocci)   a one-carpel unit of a schizocarp (q.v.).

coflorescence   within an indeterminate (polytelic) inflorescence, the aggregation of flowers on a lateral shoot arising below the main florescence, and repeating the form of the main florescence with lateral flowers and no terminal flower. See also inflorescence.

coherent   of like parts or organs, joined but only superficially.

collar   in grass leaves, a small zone at the junction of sheath and blade, the basal meristem of the blade, usually evident on the abaxial surface as a difference in colour (often pale or purplish), sometimes marked by a row of hairs.

colliculate   of a surface, covered with small rounded projections.

column   of an awn, the lower, often stouter, bent or twisted part as distinct from the upper bristle; in floral structure more generally, the fused style, stigma and stamens, as in orchid flowers (e.g. Figs. 25, 28d).

coma   of certain seeds, a tuft of hairs at the end; of the lemma in some Grasses, hairs at the apex that are usually longer than, but otherwise may be similar to, hairs on the lower part of the lemma. Adj. comate/comose.

complete   of a flower that has all parts present, i.e. perianth, androecium and gynoecium. Of a grass floret with all parts present, i.e. lemma, palea, and bisexual flower. Cf. incomplete.

compound   in general, a structure made up of several similar parts (i.e. the opposite of simple) e.g. inflorescences in which there are two or more orders of branching.

compound fruit   a category of fruit types in which the whole of each fruit is derived from more than one flower (then usually from an inflorescence), e.g. the pineapple. Sometimes also called composite or multiple fruits but the latter term usually confined to the product of one apocarpous flower. Cf. aggregate.

compound head   a type of inflorescence in which small heads, each usually with an involucre, are sessile on a short axis, e.g. some members of the Daisy Family (Fig. 126; Pl. 33l).

compound leaf   a leaf with the blade divided into two or more leaflets (Fig. 14d–j).

compound umbel   an inflorescence type; literally, an umbel of umbels. A series of umbels whose stalks arise from one point (Fig. 132a; Pl. 34b).

compression   of spikelets, the manner in which flattened—laterally compressed when flattened side to side, dorsally compressed when flattened front to back (Fig. 37). The term compressed is sometimes used in modifying other adjectives, such as compressed-trigonous (indicating a somewhat flattened three-angled structure such as a stem) or compressed-globular (spherical but flattened to some degree).

concolorous   more or less the same colour throughout, e.g. of a leaf that is the same colour on both surfaces. Cf. discolorous.

condensed   of an inflorescence, dense or compact, as opposed to e.g. lax or open.

conduplicate   with sides folded together along a midline, the upper surface inside the fold, e.g. of a leaf blade.

conflorescence   a category of inflorescence in which the main axis is of a particular nature and bears lateral branches of a different pattern. Often seen as an indefinite main axis bearing repeating lateral units that show cymose branching.

confluent   blending or running together.

conical   cone-shaped: a three-dimensional form tapering to the apex from a wide base and with a circular cross section.

connate   with like parts or organs fused together, e.g. united petals.

connective   of an anther, the tissue between and connecting the two pollen-bearing lobes (Fig. 3a). Sometimes prolonged at the apex into an ‘apical appendage’ or crest on the anther (Fig. 94).

connivent   parts converging or coming into contact, not fused.

contiguous   touching but not united, e.g. of upright branches in an inflorescence when touching (or overlapping) end to end.

continuous   in general, unjointed, e.g. of an inflorescence axis in certain grasses that remains intact, not breaking into segments up at maturity. Cf. jointed, articulate.

contracted   of a multibranched grass inflorescence such as a panicle, with the branches more or less upright and held close to the main axis. Cf. open.

contra ligule   on the leaves of some grasses, a ligule-like structure in a similar position to the normal ligule but on the abaxial side of the leaf. Also abaxial ligule, external ligule, or outer ligule.

convergent   of parts that come together gradually.

convolute   rolled inwards from one margin forming a tube (the margins thus overlapping), e.g. of a leaf blade or grass lemma. Cf. involute.

cordate   heart-shaped.

coriaceous   leathery.

corm   typically a short, underground, swollen part of a stem storing food reserves, usually formed annually, often covered in scale leaves and with the corm axis vertical, e.g. in Gladiolus (Pl. 10a) and Freesia. The term is often used more loosely for any swollen basal part of a stem or rhizome. Adj. cormose, resembling a corm.

corolla   collectively, the petals of a flower (Fig. 1).

corona   generally in flowers, a crown-like or trumpet-like outgrowth, often of the perianth (as in daffodils), but also possibly of the receptacle or stamens. In some grasses, a short crown like structure around the base of an awn, e.g. Nassella neesiana (Chilean Needlegrass). But see also crown.

corymb   a flat-topped racemose inflorescence with the lower flower stalks longer than the upper, so all the flowers are more or less at the same level (Fig. 10g). Adj. corymbose, corymbiform.

costate   usually of a surface, ribbed (e.g. a grass leaf blade).

cotyledons   the seed-leaves attached to the embryo within the seed, sometimes containing stored food (Fig. 13b, d). Adj. cotyledonary.

coumarin   an aromatic compound in some plants with an odour sometimes suggested as resembling freshly cut grass.

craspedium   a fruit type, indehiscent, initially pod-like, either breaking apart into one-seeded segments or with the valves separating as a single unit, leaving the sutures as a persistent margin.

crateriform   a three-dimensional shape, resembling a crater.

crenate   edged with rounded teeth, the sinus between adjacent teeth being acute (Fig. 18). Often describing leaf margins.

crenulate   finely crenate.

crown   In herbaceous perennial species, the region at the base to which the plant dies down each season, later to resprout. In grasses (often referring to cereals and forage species), the region at the base of the plant from which tillers arise (then more or less synonymous with rootstock), sometimes restricted to the persistent base of perennial species. Also in grasses, a small cylinder or cup-shaped ring of tissue at the top of the lemma, e.g. in some Nassella spp. (and then synonymous with corona, but some authors restrict the corona to just the apical hairs and their swollen bases on the cup-shaped ring, and the crown to the body of the ring). In forestry contexts the upper parts (foliage and upper branches) of a tree.

crustaceous   hard, thin and brittle.

cucullate   hooded, usually referring to the apex of a structure, such as a bract or perianth segment, e.g. the petals in Cryptandra amara (Fig. 73b).

culm   a specialised aerial stem, usually made up of nodes and internodes, and bearing leaves and a terminal inflorescence, and dying off after flowering (Fig. 41a). A term usually seen in reference to grasses and sedges, and often to rushes.

culm sheath   of bamboos, a sheath, usually with a reduced blade, encircling the culm (stem). Often falling as the culm elongates.

cultivar   difficult to define succinctly but usually thought of as a plant (or distinct group of plants) maintained in cultivation, whose origin or selection is primarily due to human intervention, and whose distinctive characteristics can be reliably reproduced. Usually given a cultivar name which is written in single quotes and not italicised. Abbreviation cv./cvs (singular/plural).

cultivation   in contexts such as ‘only known in cultivation’ or ‘a weed of cultivation’, is used as shorthand for ‘cultivated land’ or ‘situations where plants are grown’.

cuneate   wedge-shaped, slowly and evenly narrowing to the base (Fig. 17).

cupula/cupule   in general, a cup-shaped structure, usually small. Examples include the fused involucral bracts forming the small cup at the base of an acorn; in some sedges (e.g. Scleria spp.), the small cup-shaped structure at the base of the nut; in bamboos the depression that marks the junction of the pseudopetiole on the leaf sheath (most visible after the leaf falls). In some grasses the somewhat broadened, hollowed out apex of the pedicel may be described as cupuliform.

cushion plant   of plant habit, where internodes are short and branches numerous, giving rise to a dense, low mound. Generally an adaptation to harsh conditions.

cusp   a sharp, firm point. Adj. cuspidate, of an apex when narrowed abruptly to such a point.

cuticle   a thin outer layer on an epidermis, of fatty and/or waxy substances.

cyathium   a reduced inflorescence, surrounded by an involucre, and resembling a single flower, e.g. in Euphorbia (Fig. 78b, c; Pl. 18b).

cymbiform   boat-shaped.

cyme   as often defined, one of a group of inflorescence types in which the axes are determinate. The main axis ends in a flower, and subsequent lateral axes immediately below this flower likewise each end in a flower, and the pattern may keep repeating (Fig. 11). Adj. cymose. Some authors exclude the requirement for determinate axes, and restrict the definition to those inflorescences that will develop only one or two lateral branches from any axis, in contrast to racemose inflorescence types in which the number of lateral axes is variable and (theoretically at least) unlimited.

cymose   of certain inflorescences, a particular branching pattern. See cyme.

cypsela   a fruit type; small, indehiscent and one-seeded, derived from an inferior ovary, typical of daisies. This fruit type is sometimes included within a broad definition of ‘achene’.

deciduous   in general, falling off, usually at the end of functional life, e.g. the seasonal shedding of leaves, or of small appendages such as hairs or stipules shed before the organ on which they are growing dies or falls.

decompound   a general term for structures several times divided, e.g. of inflorescences when the main branches are repeatedly branched, or of compound leaves that are again divided. The number of orders of branching is sometimes specified at two or more, sometimes three or more.

decumbent   of a shoot, prostrate for much of its length becoming more upright towards the apex.

decurrent   in general, extending downwards, e.g. of a leaf with the stalk margins or base extending down from the point of attachment, forming wings or flanges down the stem (Fig. 15).

decussate   an arrangement of opposite leaves, with each pair at right angles to those above and below (Fig. 15).

definite   of an axis which has a defined conclusion, as in an inflorescence axis ending in a flower. Also determinate. Cf. indefinite.

deflexed   bent abruptly downwards from the point of attachment, e.g. of hairs, leaves, bracts, branches etc. Cf. reflexed.

dehiscence   the splitting, or opening of a structure to release the contents, e.g. of an anther to release the pollen or fruit to release seeds. Adj. dehiscent.

deltate   a two-dimensional shape, triangular, with sides more or less equal in length.

deltoid   a three-dimensional figure with triangular faces, but sometimes used as synonymous with deltate.

dentate   toothed, e.g. of a leaf margin, the teeth pointing outwards more or less perpendicular to the outline of the leaf (Fig. 18). Dim. denticulate, finely toothed.

depauperate   of a plant or part of a plant, stunted in growth, impoverished.

determinate   of plant growth, parts that come to a definite end, e.g. a rhizome that soon turns upwards as a new shoot, an inflorescence axis that concludes in a flower. Also definite. Cf. indeterminate. Referring to inflorescences within the terminology system of Troll (see Weberling, 1989) ‘monotelic’ is effectively the same.

diadelphous   of stamens, united by their filaments in two groups. Cf. monadelphous. Sometimes more generally meaning arising or borne in two bundles or groups.

diaspore   the dispersal unit of a plant e.g. the seed, or fruit, or part of a fruit, that is shed and may give rise to a new plant.

dichasium (plur. dichasia)   an inflorescence (or part thereof) with a cymose branching pattern in which an axis ends in a flower and two lateral flower buds develop below it. Some authors refer to the resulting three-flowered unit as a triad. A dichasium is said to be compound if this pattern is repeated (Fig. 11b), although some texts consider the addition of ‘compound’ to be unnecessary, extending the basic definition to include subsequent branches.

dichotomous   of branching, forked, in which the branches are of equal size and often branch again in the same way. Of botanical keys when made up of couplets each of two mutually exclusive statements.

dicots   abbreviation of Dicotyledons (see Chapter 6).

dicotyledons   in older classifications, the major subgroup of Flowering Plants having seeds with two cotyledons. Formally spelled Dicotyledones or sometimes Dicotyledoneae. (See Chapter 6, abbr. dicots.) Now considered not to represent one lineage, and divided into several groups, the largest of which is the eudicotyledons (abbr. eudicots). Species in this latter group form a clade, and share a particular pollen type.

digitate   diverging from a (more or less) single point, e.g. the branches of an inflorescence in some grasses (Fig. 41a).

dimorphic/dimorphous   of two forms, similar in kind but dissimilar in shape or structure, e.g. of the spikelets in the grass Dimorphochloa which has both chasmogamous and cleistogamous inflorescences.

dioecious   of a species, or sometimes of a population of plants, in which flowers are unisexual, and individual plants bear only one sex, e.g. many members of the family Restionaceae, the common grass of coastal sands Spinifex, and many introduced trees such as birches, and willows. Noun dioecy.

diploid   of an organism, having two complete sets of chromosomes, normally one set from each parent. Cf. haploid.

disarticulation   see articulation.

disc   in a flower, a structure usually associated with the ovary either at the top or base, or lining the floral tube, and often secreting nectar (and in this sense sometimes spelled disk). In some sedges (e.g. Scleria), a lobed or cup-like structure at the base of the ovary, persisting into the fruiting stage, sometimes indistinct, sometimes large enough to more or less cover the fruit. In a radiate head of a daisy, the tubular florets collectively.

disc florets   the tubular florets in the centre of a radiate flowerhead of a daisy.

disciform   an inflorescence type in some daisies in which the central florets are bisexual and have tubular corollas, the marginal florets differing in gender and/ or corolla type, e.g. female or neuter, with corollas filiform or lacking (e.g. Figs. 122, 123; Pl. 33j). The resulting inflorescence may resemble a discoid head, and some authors include it within this type.

discoid   an inflorescence type in some daisies in which the florets all have tubular corollas, and are all bisexual (e.g. Figs. 120, 121), or sometimes all functionally unisexual.

discolorous   usually of leaf blades etc., when a different colour on upper and lower surfaces. Cf. concolorous.

dispersal unit   that part of the plant which is shed or released and may give rise to a new plant, e.g. seed, or fruit (with or without accessory structures such as bracts), or burr etc.

dissected   of a leaf, with the lamina divided into deep lobes or segments.

disseminule   a general term for part of a plant that serves for dissemination (spread), often seeds or spores etc. but also e.g. rhizome fragments, bulbils, etc.

distal   situated at or towards the end of a structure that is furthest from the structure’s point of attachment. Cf proximal.

distichous   of leaves (Fig. 15), glumes etc., arranged in two opposite rows (and thus in one plane), e.g. the florets in many spikelets (Fig. 38d; Pl. 13b). Noun distichy.

distinct   see free.

divaricate   widely spreading, e.g. of a multi-branched shrub in which the branches spread out at an angle approaching 90 degrees.

divergent   of structures that gradually spread widely, e.g. awns on some grass florets, veins in some leaves. Of anther lobes attached at the apex to the filament, their bases spreading apart.

domatia   small pockets, usually in the axils of the main leaf veins on the lower surface, often partly enclosed by leaf tissue or hairs.

dorsal   pertaining to or situated at the back. Of a lateral organ, the abaxial surface. Cf ventral.

dorsal compression   see compression.

dorsifixed   of an anther, with the filament attached to the back of the anther (Fig. 3c; Pls. 3d, 4i).

dorsiventral   of an organ with different back and front or upper and lower surfaces, e.g. some leaf blades. The difference is sometimes defined as structural.

double   of flowers, having more than the usual number of petals; quite common in cultivars developed for ornament such as many camellias, fuchsias and roses.

drepanium   an inflorescence type, usually thought of as a compound monochasium in which the successive branches and flowers all lie on one side of the inflorescence and in one plane. This inflorescence type is sometimes seen in Juncus species.

drupe   a fleshy fruit with a hard endocarp enclosing the seed, a fleshy mesocarp, and the exocarp forming a ‘skin’, e.g. cherry or plum.

e-   a prefix meaning without (as in ebracteate, q.v.).

ear   of grasses (usually only of cereals such as wheat), the inflorescence.

ebracteate   without bracts.

eccentric   off centre, e.g. the attachment of the awn to the lemma in Nassella trichotoma (Serrated Tussock). Sometimes seen as ‘excentric’.

elaiosome   an oil-bearing appendage, or modification of part of a dispersal unit, that is attractive to insects, and may thus facilitate dispersal.

eligulate   lacking a ligule.

ellipsoid   a three-dimensional figure with an elliptical longitudinal section.

elliptical /elliptic ellipse-shaped, e.g. of a leaf where length is about 2 to 3 times width, broadest in the centre and tapering equally to each end (Fig. 16).

elongate   lengthened, extended.

emarginate   lacking a distinct margin; or of an apex (e.g. a leaf), notched at the tip. Some authors specify the notch to be sharp or abrupt (Fig. 17). Cf. retuse.

embryo   the rudimentary plant within a seed.

endemic   of a taxon with respect to its distribution, naturally restricted to a specified area or country.

endocarp   the innermost wall of the pericarp, which often becomes hardened as in plums and cherries.

endosperm   a food reserve, associated with the embryo in the seeds of Flowering Plants. Adj. endospermic.

ensiform   shaped like the blade of a sword.

entire   of a margin, continuous and undivided, unbroken by lobes, indentations, teeth, etc.

environmental weed   see weed.

ephemeral   a plant that completes its life cycle in a short time when conditions are favourable.

epi-   a prefix meaning upon.

epicalyx   a whorl of sepal-like bracts outside and often attached to the calyx, the bracts usually alternating with the sepals (Fig. 99a; Pl. 21g, h, i).

epicormic   of buds that lie dormant under the bark of some trees, such as eucalypts, and grow when the tree is damaged or defoliated, e.g. by fire.

epicotyl   the part of the plant axis between the cotyledonary node and first foliage leaves (Fig. 13b).

epidermis   the outermost layer of cells, usually single, on leaves, young shoots etc.

epigynous   of a flower, with the petals, sepals and stamens arising above the level of the ovary (Fig. 8b; Pl. 5a). Thus the ovary is inferior.

epipetalous   of stamens that are attached to the petals.

epiphyte   a plant growing on another but not deriving food from it.

episepalous   of parts borne upon the sepals.

epistomous   of stomata occurring on leaves, when confined to the upper (adaxial) surface. Cf hypostomous, amphistomous.

epitepalous   of stamens that are attached to the tepals, e.g. as in Grevillea and some monocots.

equitant   an arrangement of leaves when borne in two opposite rows on the stem, the bases overlapping, and with the blades usually compressed or closely folded along the midline, giving each tuft of the plant a distinctive flattened appearance, e.g. in many Iridaceae and in Juncus ensifolius (Swordleaf Rush).

ericoid   of leaves that are small and narrow, with the blade margins recurved so the underside is obscured, as in some members of the Ericaceae (Heath Family).

erose   often of an apex or margin, irregularly eroded or torn.

escape   used as a noun to refer to a plant or species that has become established beyond its natural range by spreading from cultivation. Sometimes seen as ‘garden escape’.

eudicotyledons   see under dicotyledons.

evergreen   of a plant or species that retains its leaves throughout the year, without shedding them seasonally.

excentric   see eccentric.

excurrent   in general, extending out beyond an apex or margin, as when a midrib extends beyond the apex of a bract.

exocarp   the outer layer of the pericarp, e.g. the skin of a cherry.

exotic   used as a noun to refer to an introduced plant or species; not native. See also alien.

exserted   protruding, e.g. of anthers projecting beyond a tubular corolla, or an awn protruding beyond enclosing glumes.

exstipulate   without stipules.

external ligule   contra ligule (q.v.).

extra-axillary   of a bud that is not produced in a leaf axil.

extra-floral nectary   nectar-secreting gland not associated with flowers, e.g. on a petiole or lamina.

extravaginal   of a lateral shoot that breaks through the base of the subtending leaf sheath, thus growing up outside the leaf sheath, characteristic of certain grasses. Cf. intravaginal, infravaginal.

extrorse   referring to dehiscence of anthers when facing away from the central axis of the flower. Cf. introrse.

facultative   adaptable in mode or response (e.g. of habit or nutrition) as conditions require or allow. Cf. obligate.

falcate   a two-dimensional shape, sickle-shaped.

falls   in the genus Iris, the outer tepals which are narrow at the base, each expanding upwards into a broad, usually arching or pendulous limb.

family   a taxonomic group of one or more related genera; a sub-division of an order. The names of botanical families end in ‘-aceae’ (except for eight alternative names, accepted under the International Code of Nomenclature for Algae, Fungi and Plants, e.g. Gramineae an accepted alternative for Poaceae).

fascicle   in general, a cluster or bundle of similar parts, e.g. of culms, branches or spikelets, etc.

fastigiate   of plant habit, with stem(s) and main branches more or less erect, or lateral branches held close to an upright main axis.

fibre   in general, an elongated strand resembling a thread of cotton or string. As a component of plant tissues, one of the main cell types making up sclerenchyma.

fibrillose   in general, composed of fine fibres. Sometimes referring to a structure (such as a rhizome scale) disintegrating and leaving the veins more or less intact.

fibrous   composed of or including fibres. Dim. fibrillose. Often used in a general way to indicate structures that resemble, or are made up of elongated strands, such as a ‘fibrous root system’, or ‘fibrous bracts’ (where the bracts have mostly disintegrated leaving behind the strands of old vascular tissue).

filament   the stalk of an anther (e.g. Figs. 1b, 3a; Pl. 1c).

filiform   thread-like, i.e. long, thin and cylindrical. A type of tubular floret in some daisies.

fimbriae   rather coarse hairs or elongated processes, often forming a fringe.

fimbriate   of a margin, fringed (the hairs generally coarser or larger than in a ciliate margin).

fistula (from Latin, a pipe or tube)   in general, a hollow-centred structure. In grasses most often referring to hollow culms. Adj. fistulose.

flabellate   fan-shaped.

flag leaf   in grasses, the uppermost leaf on the culm, below the inflorescence.

flaps   of a palea when two-keeled, that part to the outside of each keel, these often folded inwards enclosing the caryopsis.

flexuose   having a wavy or zigzag form, bent alternately in opposite directions.

flora   collectively, the plants of an area; or a book about the plants of an area, usually with descriptive entries following a system of classification, and keys to facilitate identification.

floral leaves   in general, leaf-like structures associated with inflorescences. Could include bracts or spathes etc.

floral tube   in a flower, a structure appearing as the united bases of perianth parts and stamens, and often tubular (Fig. 9). Also referred to as the receptacle, torus, hypanthium, floral cup and calyx tube. In flowers with an inferior ovary such as Fuchsia (Fig. 80; Pl. 19d) the floral tube could be considered united with and projecting above the ovary. In Prunus with a superior ovary (Fig. 72; Pl. 3e), the floral tube is free from but surrounds the ovary. Floral tube is a general term not implying any particular origin, whereas ‘receptacle tube’ suggests an outgrowth of the receptacle bearing the perianth and stamens.

florescence   of an indeterminate (polytelic) inflorescence, the aggregation of flowers on the main axis. In a compound (branching) inflorescence, this shoot becomes the main florescence with lower branches (coflorescences) repeating the same pattern of lateral flowers and no terminal flower. Thus the florescence can be thought of as the ‘basic unit’ of a polytelic inflorescence. See also inflorescence.

floret   in general, a small flower; mainly used in reference to the flowers making up the heads (inflorescences) in the Daisy Family, and the floral units of the Grass Family, but should not be taken as implying any particular connection between the two families. In grasses a complete floret consists of the flower and its subtending lemma and palea and, in spikelets with more than one floret, a segment of the rachilla. A vestigial floret in grasses may comprise only a reduced lemma.

foliaceous   leaf-like, usually in texture, shape etc.

foliar   pertaining to the leaves.

follicle   a fruit type, dry, containing one to many seeds, derived from a flower with a single carpel, and splitting along one side at maturity. The pericarp is hard and tough, or leathery. The fruit type of Banksia and Grevillea and some other members of the family Proteaceae (Fig. 48b).

fovea   a pit or hollow. Adj foveate, pitted. Dim. foveolate, marked with small pits.

free   not joined laterally to a similar member, e.g. free petals. Some authors restrict this term to refer to unlike parts (e.g. stamens free from petals), and use the term ‘distinct’ to refer to separate like parts.

free central   of placentation, the placenta arising centrally from the base of a unilocular ovary (Fig. 5h; Pl. 25i).

frondose   leafy.

fruit   the ripe ovary of a flowering plant, sometimes including accessory structures, e.g. the beak and pappus of dandelion and other daisies, or the persistent bracts of some grasses.

fugacious   lasting only a short time, e.g. the perianth of some species in the Iridaceae (Iris Family).

funicle   the stalk of an ovule attaching it to the placenta, later becoming the stalk of the seed (Fig. 5a).

fusiform   a three-dimensional shape, spindle-shaped, narrowly cylindrical but widest in the centre and tapering towards each end.

gamete   a haploid cell involved in sexual reproduction.

gamopetalous   of a flower, with united petals.

gamosepalous   of a flower, with united sepals.

garden escape   a plant species introduced for gardens, which now grows and reproduces freely outside cultivation (and beyond its natural range). See also naturalised and alien.

gemmiparous   of a bract (e.g. at the base of a bamboo pseudospikelet) which subtends a bud in its axil.

geniculate   bent rather abruptly, as in a knee joint.

genus (plur. genera)   in classification, the main rank between family and species. A taxonomic group of species which resemble each other more closely than they resemble other such groups.

generic name   the name of a genus, e.g. Acacia, Eucalyptus.

germination flap   in the fruits of some grasses, a small area of tissue at the base of the persistent lemma, often shaped like a horseshoe in outline, through which the first root of the seedling appears.

gibbous   pouched; with a pouch-like swelling.

glabrescent   becoming glabrous, e.g. of a structure initially bearing hairs that erode or fall over time. Sometimes used in the sense of ‘nearly glabrous’.

glabrous   of a surface or structure, without hairs or other trichomes or covering. Some authors also include ‘smooth’ in the definition.

gland   an organ or tissue with a secretory function, e.g. secreting oil, nectar, resin or water. Glands may be on the surface or embedded in surrounding tissue, or raised above it on a stalk. Dim. glandule.

glandular   of a structure, possessing glands or including an area of secretion-producing tissue.

glandular hair   a hair involved in glandular secretion (the secretion usually appearing as a tiny droplet at the hair tip).

glaucescent   becoming glaucous over time. Sometimes used in the sense of ‘somewhat glaucous’.

glaucous   of leaves, stems etc., that have a bluish or greyish appearance, usually caused by a waxy substance on the surface.

globose   a three-dimensional shape, spherical.

glochidiate   bearing barbed bristles.

glomerule   a dense, compact cluster, e.g. of small subsessile flowers. Adj. glomerate.

glumaceous   glume-like, i.e. resembling a glume in shape, texture, and perhaps colour, e.g. sometimes seen describing tepals in Juncus (Rush) and Luzula (Woodrush).

glume   a specialised bract. In grass spikelets, usually two at the base (the lower and upper glumes, Fig. 38d) these not subtending a flower. The upper glume is generally the larger; grass glumes are said to be ‘inverse’ when the lower glume is larger than the upper. In bamboo spikelets, several ‘glumes’ might be present but these are of uncertain affinity, and in some cases transitional glumes grade into sterile lemmas. The term ‘flowering glume’ is sometimes seen in older texts on grasses referring to the lemma. Within the spikelets of sedges and members of the Restionaceae, one glume subtends each flower, although this usage is challenged by some authors who prefer the use of ‘floral bract’ or ‘scale’ in this context. Dim. glumella.

grade   a general term for taxonomic groups placed together for (temporary) convenience but considered not to be monophyletic (q.v.). Usually seen in discussions relating to classification. Not restricted to any particular rank.

grain   a common term for the fruit of most grasses, and then equivalent to caryopsis, but often used rather loosely and may include attached husks, or be used to refer to the seeds of species in which the seed is free from the pericarp, e.g. Sporobolus.

granular   of a surface, covered with tiny rounded projections, and thus not completely smooth.

gregarious flowering   of bamboos, when many individuals of a species flower concurrently after a (usually lengthy) period of purely vegetative growth. Equivalent to ‘mast flowering’.

gynandrous   of a flower in which the stamens and styles have united to form a column, as in orchids.

gynecandrous (gynaecandrous)   of bisexual spikes within Carex inflorescences in which female flowers are above the male in each spike. Cf. androgynous.

gynobasic   of a style that arises from near the base of a deeply lobed ovary (Fig. 6c).

gynodioecious   of a species, with female flowers and bisexual flowers on separate plants.

gynoecium   that part of a flower, usually centrally placed, consisting of one or more free or united carpels (Fig. 1), and almost universally referred to as the ‘female’ part of the flower. (The term ‘female’ more correctly applies to that part of an ovule made up of cells that have undergone cell division during which the chromosome number is halved. These cells are thus haploid.)

gynomonoecious   of a plant or species in which individual plants bear separate female as well as bisexual flowers.

gynophore   within a flower, a stalk which raises the gynoecium above the points of insertion of the sepals, petals and stamens. Used for the stalk below the ovary in female flowers of Typha spp. May remain attached to the base of the fruit.

habit   of a plant, the general external form, appearance or shape. Of a species, the general external form usually observed.

half inferior   of an ovary, when only partly projecting above the level of attachment of perianth parts and stamens, thus the lower part embedded in the receptacle (Pl. 20i). Ovaries of this type are often simply regarded as inferior.

haploid   having one set of chromosomes. Cf. diploid, polyploid.

hastate   a two-dimensional shape, halberd-shaped, e.g. the base of a leaf blade with a more or less triangular lobe projecting outwards from each side (Fig. 17).

haustorium   in parasitic plants, an organ developed for penetrating the host’s tissues.

head   an inflorescence type, made up of small sessile flowers, often surrounded by an involucre (as in most daisies), but often used to refer to any compact group of small flowers forming either the whole, or part, of an inflorescence (Fig. 10, d, e). See also capitulum.

helicoid cyme   see bostryx.

herb   a non-woody plant (but not including mosses or liverworts). In more general use, a plant of medicinal or culinary value, that is not necessarily non-woody.

herbaceous   of plant habit, not woody, i.e. without woody tissue derived from secondary thickening. Of the nature of plant parts (e.g. bracts), relatively soft and usually green.

herbarium   a collection of preserved, usually dried, plant material. Also an institution or building in which such collections are stored. Most countries of the world have state or national herbaria, often associated with botanic gardens.

hermaphrodite   having both functional male and female organs; usually referring to flowers with both stamens and carpels. Equivalent to bisexual.

hesperidium   a type of fleshy fruit, with axile placentation, and the pericarp with a leathery rind and internally fleshy. In the orange, lemon, etc. the flesh is made up of swollen fluid-containing hairs, which fill the loculi.

heterogamous   of parts that differ in sexuality, e.g. of florets in the head of a daisy with bisexual disc florets and male or sterile ray florets. Of the spikelet pairs in some grasses where one spikelet is bisexual and the other male or neuter. Cf. homogamous.

heterogeneous   of parts or plants, when of several kinds, not uniform. Cf. homogeneous.

heteromorphic   of parts when not of the same structure or appearance, e.g. spikelet pairs in some grasses. Cf. homomorphic.

hexaploid   of a plant or species, with six sets of chromosomes. Cf. polyploid.

hilum   on the seeds of most plants, the scar on the seed coat at the point where the seed broke away from its stalk. In grass fruits (where the seed coat is usually fused to the ovary wall) the hilum is usually visible on the outside of the fruit. Adj. hilar, plur. hila.

hirsute   of a surface, bearing stiff, rather long, usually erect or ascending hairs.

hispid   of a surface, bearing coarse, bristly hairs. Dim. hispidulous.

hoary   of a surface, covered with pale, very short, intermeshed hairs.

homogamous   in general, producing sexually similar flowers. Of the spikelet pairs in some grasses in which both spikelets are sexually similar. Cf. heterogamous.

homogeneous   of parts or plants, when of the same kind, uniform. Cf. heterogeneous.

homology   in assessing morphological structure, a condition indicative of the same phylogenetic, or evolutionary origin, but not now necessarily the same in present structure or function. Adj. homologous, of parts that have the same developmental origin, but not necessarily now with the same appearance or function.

homomorphic   of parts when of the same form or shape. Cf. heteromorphic.

hull/husk applied to the scales (possibly glumes, lemmas, paleas) covering the grain of grasses. Most often seen referring to cereal grain in agricultural contexts.

hummock   a type of habit of certain grasses. A more or less rounded clump up to c. 1 m tall and 3 m diameter in which branched culms radiate outwards and bear leaves (often sharply pointed) towards their tips. Typically drought tolerant species of dry inland habitats in Australia.

hyaline   of the nature of a bract, lemma etc., delicate and thin often to the point of being transparent, usually veinless.

hybrid   usually within one genus, the offspring of plants from two different species that interbreed. Occasionally hybrids are intergeneric.

hypanthium   the floral tube (q.v.).

hypo-   a prefix meaning below.

hypocotyl   in a seed or seedling, the part of the plant axis below the cotyledonary node but above the root (Fig. 13b).

hypogynium   in the fruit in certain sedges, a hardened disc-like structure at the base.

hypogynous   of a flower in which the other parts arise around the base of the ovary (Figs. 1, 8a). Of an organ, arising at the base of the ovary, e.g. a scale or gland.

hypostomous   Of a leaf blade, bearing stomata on the lower (abaxial) leaf surface. Cf amphistomous, epistomous.

imbricate   of organs that overlap, e.g. bracts or petals.

imparipinnate   of a pinnate leaf, with an uneven number of pinnae including one terminal pinna (Fig. 14h).

imperfect   of flowers (or grass florets), with one of the usual series of parts (e.g. stamens) absent.

impressed   usually of veins, when sunken into a surface.

incised   of a margin (often of a leaf blade) when cut rather deeply and sharply (about half way or more to the midvein) into pointed lobes (Fig. 18). An inconsistently defined term—cuts sometimes cited as irregular, sometimes even.

included   of parts when not projecting beyond an enveloping structure, e.g. of stamens within a corolla tube.

incomplete   of a flower with one or more series of parts missing, i.e. lacking a perianth, androecium or gynoecium. Of a grass floret lacking one or more parts. Cf. complete.

incrassate   thickened.

incurved   curved inwards or upwards, e.g. of a leaf margin curled in towards the adaxial surface (Fig. 17). Cf. recurved.

indefinite   of an axis that does not have a defined conclusion, as in an inflorescence axis not terminated by a flower. See also blastotelic, indeterminate. Cf. definite. Of floral parts, e.g. stamens, when numerous without a fixed number.

indehiscent   of fruits that do not split open to release the seeds.

indeterminate   of plant growth, a part that may continue growth more or less indefinitely without a defined conclusion (e.g. rhizome, shoot, floral axis etc.). See also indefinite. Cf. determinate. When referring to inflorescences within the terminology system of Troll (see Weberling, 1989) polytelic has effectively the same meaning.

indigenous   referring to a plant, species, vegetation type etc., that occurs naturally in a specified region.

indumentum   collectively, the surface covering of hairs or scales etc. on a part of a plant.

induplicate   folded inwards.

indurate   hardened and toughened.

indusium   a cup-like structure at the end of the style enclosing the stigma, e.g. in the family Goodeniaceae (Fig. 115; Pl. 5e, i). In certain ferns, a protective covering over the spore-bearing parts.

inferior   of an ovary, with perianth parts and stamens attached above it. Epigynous flowers have inferior ovaries (Fig. 8b; Pl. 5). Cf. superior.

inflated   in general, of a part that is enlarged around another, e.g. of a calyx tube very loosely enclosing a flower or fruit; of leaf sheaths of certain grasses when expanded so there is noticeable space between the sheath and enclosed culm.

inflorescence   a general term for that part of a plant which produces an aggregation of flowers with associated axes and bracts (Figs. 10, 11). Thus a plant could bear more than one inflorescence, each separated by regions of vegetative growth. Numerous different types of inflorescence are recognised, distinguished by such things as degree of development of branches and flower stalks, branching pattern, sequence of flower opening, etc. In grasses, the inflorescence consists of the spikelets, branches and main axis above the uppermost culm node.

[In the specialist literature dealing with inflorescences, a suite of more precisely defined terms is being explored. Researchers have expressed a need for a terminology that facilitates accurate and meaningful comparisons between different species and between taxonomic groups. Some new approaches have been criticised as unduly theoretical, at the expense of providing terms that can be used in a purely descriptive way without a theoretical overtone. Some of the terms are introduced here, but it remains to be seen to what degree these and others are taken up by authors of floras in the future. Consider an inflorescence with flowers borne on a central main axis and on a number of lateral branches. Above the uppermost lateral branch, the flowers on the main axis appear in a particular arrangement, and the lateral branches can be seen to repeat this pattern, usually fairly closely. This compound inflorescence system of an arrangement of flowers occupying the end of the main axis combined with lateral axes that appear to mirror the main axis may be referred to as a synflorescence. When the main and lateral axes do not each end in a flower (i.e. they are indeterminate) the synflorescence is said to be polytelic (many-ended). Conversely if these axes end in a flower (determinate) the synflorescence is said to be monotelic (one-ended). The lateral branches, in appearing to repeat the arrangement of the main axis, may be called paraclades/paracladia (repetition shoots). In polytelic synflorescences, the aggregation of flowers on the main axis is termed the main florescence, while those of the lateral branches are coflorescences. Thus the florescence can be thought of as a ‘basic unit’ of a polytelic synflorescence. In families such as the Grasses and Sedges, the spikelets can be taken as indeterminate flowering axes and thus be thought of as florescences; the spikelet terminating the main axis would be the main florescence. In this context, the stalk of a spikelet could reasonably be called a peduncle. Discussion of inflorescence structure, together with numerous terms denoting different inflorescence types, can be found in the works of Briggs and Johnson (1979), Endress (2010), and Weberling (1989) listed in the References.]

inflorescence bract   a bract subtending an inflorescence or sometimes subtending a part of an inflorescence.

inflorescence prophyll   within some Carex (Sedge) inflorescences, a prophyll (generally resembling a perigynium/utricle) at the base of the axes above the primary lateral branches. The primary axes may have a prophyll of a different form at the base, referred to as a cladoprophyll.

infravaginal   of a lateral branch that emerges through a girdle below its subtending sheath. A form of extravaginal branching found in a number of bamboos.

infructescence   effectively the fruiting stage of an inflorescence.

innovation   of grasses, a basal shoot, an immature tiller, usually referring to a vegetative shoot, sometimes restricted to those of perennials.

inrolled   e.g. of leaves or bracts etc., with the margins rolled inwards over the upper surface towards the midline.

intercalary   of growth when taking place in an axis between (but not at) the apex and base, e.g. the meristems providing growth of the internodes of a Grass stem. Also seen describing an inflorescence when between two regions of vegetative growth (e.g. Callistemon, Fig. 81).

intercarinal   see interkeel.

intercostal   of the surface or region between the veins, e.g. of a leaf or bract.

interkeel   the region between two keels, as in the central part of the palea in many grasses.

intermast   in bamboos, the period of vegetative growth between flowering events.

internerve   the surface or region between adjacent nerves, e.g. of a glume.

internode   the section of stem between two successive nodes (Fig. 13).

interpetiolar   e.g. of stipules, when occurring between the bases of the petioles of opposite leaves.

interrupted   in general, with a break in continuity, e.g. of a spike-like panicle in which the axis is visible between the lower branches.

intravaginal   of a new vegetative shoot that grows up within the subtending leaf sheath, emerging at the top of the sheath. A term mostly seen describing grasses. Cf. extravaginal, infravaginal.

introduced   of a plant or species that is brought in from another region or country, usually intentionally for a specific purpose, thus not indigenous.

introrse   of anthers that open inwards towards the centre of the flower. Cf. extrorse.

inverse   of glumes in some grass spikelets, the lower glume longer than the upper.

involucel   within a compound umbel, refers to a whorl of bracts subtending each individual umbel.

involucral bract   a member of an involucre, but the term sometimes applied to a solitary bract below an inflorescence as in some Sedges.

involucre   most often ring(s) or series of bracts (sometimes few), usually surrounding the base of an inflorescence, typical of the Daisy Family. Adj. involucral. Also used in the Sedge Family where the bracts subtending an inflorescence may be leaf-like or glume-like or setaceous, e.g. for leaf-like bracts subtending the inflorescence in some Cyperus species. In the Grass Family may refer to bristles or spines surrounding groups of spikelets as in Cenchrus.

involute   of a leaf blade or bract etc., with both margins rolled inwards (i.e. towards the centre line across the upper surface, Fig. 17). Cf. convolute, revolute.

irregular   of the symmetry of some flowers, when radially asymmetrical, i.e. with none or only one plane of symmetry (e.g. the flowers of many orchids) (Fig. 2d–f). Also zygomorphic.

isodiametric   of a structure (e.g. a cell) that has equal diameters, or is of equal size along the major axes.

iterauctant   of the inflorescences of some bamboos, when made up of pseudospikelets that have buds in the axils of lower bracts, the buds potentially growing out into further pseudospikelets. Can be roughly understood as ‘repeatedly growing’ or ‘repeatedly increasing’. Cf. semelauctant. The resulting inflorescence can appear as a dense compound cluster of apparent spikelets with much-shortened supporting branchlets, and ‘extra’ glume-like bracts at the base of each apparent spikelet. Each ‘apparent spikelet’ (a pseudospikelet) is made up of several basal bracts subtending buds, a variable number of glumes, and a terminal spikelet.

jointed   e.g. of an axis which includes joints marking the points at which it will break up. Also articulate. Cf. continuous.

juvenile leaf   a leaf on a young plant, usually differing in form to leaves of the same plant when adult. A common occurrence in the genus Eucalyptus (Fig. 84).

keel   of the corolla in pea flowers, the two more or less united lower petals (e.g. Figs. 65, 66). In general, a ridge along a fold, e.g. at the back of a grass lemma such that the lemma resembles the shape of a small boat (Fig. 38e).

kernel   often refers to the seed within the hard endocarp of a drupe (e.g. the seed of a cherry), but also seen in agricultural contexts referring to the grains (caryopses) of Zea mays (Corn).

labellum   of an orchid flower, the petal opposite the column, usually different in appearance to the two lateral petals (Figs. 24–8). Sometimes also used to describe modified petals in other groups.

labiate   of a corolla, with one or more petals forming a lip. See also bilabiate.

lacerate   of a margin (e.g. a leaf blade) appearing cut or torn into irregular pointed lobes (Fig. 18). Not always consistently defined.

laciniate   of a margin (e.g. a leaf blade) appearing as though slashed or cut into rather narrow, pointed lobes.

lacuna (plur. lacunae)   in general a gap or space, e.g. an internal air space between cells of a leaf blade, or in stem tissues.

ladder-fibrillose   of old disintegrated sheaths (typically of some Carex spp.) where the fibrous remains of the vascular tissue form a pattern with a central vertical strand from which more or less horizontal lateral strands arise.

lageniform   urn-shaped.

lamina   an alternative term for the blade of a leaf or bract, as distinct from the sheath or petiole.

lanate   woolly.

lanceolate   a two-dimensional shape (e.g. a leaf) where length is about five times width, the widest part below the centre, and tapering to each end (Fig. 16).

lanceoloid   a three-dimensional figure, having a lanceolate silhouette.

lateral compression   see compression.

latex   a milky juice that exudes from cut or broken parts of some plants, e.g. milk thistles and dandelions.

lax   usually of an inflorescence, in which case meaning not dense or congested, and thus loosely arranged, possibly drooping. Sometimes referring to a leaf or plant habit, and then used as contrasting with stiff or rigid.

leaf   an outgrowth of a stem, usually flat and green with a stalk (petiole), or in grasses and similar plants a sheath, supporting an expanded blade (Fig. 14). The main function is food manufacture by photosynthesis.

leaflet   one of the segments of a compound leaf (Fig. 14).

leaf sheath   of the leaves of grasses and many other grass-like species, the lower part of the leaf (often forming a cylinder) which encircles the stem, and supports the blade. In some families (such as Restionaceae) the leaves are reduced to more or less bladeless sheaths.

legume   a dry fruit derived from a single carpel, which splits along both sutures at maturity. Also used in a general way for any plant producing such fruit, typically a member of the family Leguminosae.

lemma   in grass florets, the outermost and (usually) larger of the two bracts enclosing a flower (Figs. 38e, 39; Pl. 13b, e). In vestigial florets the (reduced) lemma is often the last remaining element.

lenticular   a three-dimensional figure, shaped like a lentil or biconvex lens, i.e. more or less circular in outline and thicker in the centre than the margin.

leptomorph   of rhizomes in some bamboos, elongated, slender, monopodial. Cf. pachymorph. Species with this rhizome form are commonly called ‘running bamboos’ in horticultural contexts.

liane   a woody climbing or twining plant, not parasitic on its support plant, although may in time be detrimental by restricting the support’s growth.

lignin   a complex of phenolic compounds found in cell walls of certain tissues, imparting strength and stiffness. A major component of woody tissue, also found in bamboos, and some other grasses.

lignotuber   a woody swollen structure at the base of a stem, at or below ground level, that can facilitate regeneration if the aerial parts of the plant are damaged. Common in the genus Eucalyptus.

ligulate   possessing a ligule. Also a two-dimensional shape when elongated and with parallel sides, and usually described as strap-shaped.

ligule   of most grasses and some sedges, a membranous outgrowth or ring of hairs at the junction of the leaf sheath and leaf blade on the adaxial (upper) side (Fig. 38b). In many sedges the ligule is mostly fused to the blade, with just a small free rim. An abaxial ligule (also contra ligule) occurring in some grasses is of similar structure but on the outer (lower) side of the sheath-blade junction. Of the corolla of some florets in daisies, an elongated strap-shaped extension (Figs. 116–118, 124–5; Pls. 32, 33). Adj. ligulate.

limb   of a petal, the wider upper part from a narrow base; or the upper, usually spreading, section of a corolla of united petals (Fig. 2i, j). Of an awn in some grasses, the finer upper part usually borne on a firmer, often twisted, lower column, and then synonymous with bristle.

linear   a shape, long and narrow, with parallel sides, e.g. of a leaf when length is longer than about eight times width and sides are parallel (Fig. 16).

lingula   a small tongue-like extension, e.g. on the apex of the leaf sheath opposite the blade in some sedges. Adj. lingulate.

lobe   in general, any division or segment of an organ Examples include the free upper part of parts fused at the base (e.g. calyx lobe, corolla lobe); part of a dissected leaf; a projection of tissue from a structure with an otherwise entire margin, as in lobes from the apex of a grass lemma.

loculicidal   of dehiscence in which splitting occurs longitudinally along lines corresponding to the midline of each internal cavity, e.g. of a capsular fruit, each valve consisting of part of the outer wall of adjoining carpels. Cf. septicidal.

loculus (plur. loculi/locules)   a chamber or cavity, e.g. within an ovary containing one or more ovules (e.g. Figs. 4a, 23d; Pls. 9d, 11c). Sometimes seen as ‘locule’.

lodging   a condition in which plant stems are caused to bend near the base and lean or lie flat on the ground. Most often seen in reference to cereal grasses.

lodicule   in grasses, one of the small scales within the lemma and palea at the base of the flower, often interpreted as a reduced perianth member (Pl. 13e). Most grasses have two lodicules located on the side of the flower adjacent to the lemma. Bamboo flowers typically have three lodicules.

lomentum   generally used to refer to a pod-like indehiscent fruit, derived from a single carpel, that develops constrictions between the seeds and, at maturity, breaks into one-seeded segments (although originally defined more broadly as a legume-like fruit that breaks up other than by separating into two halves, or does not break up at all). Seen in the Legume Family. Sometimes written ‘loment’.

longitudinal section   effectively a ‘thin slice’ taken through the long axis of a structure or organ (e.g. an ovary or leaf) then viewed from the side. Often abbreviated to L.S. (Pls. 1f, 3f.) See also Figure 21. Cf transverse section.

lorate   strap-shaped, moderately long with parallel sides.

lumen   an internal cavity.

lyrate   lyre-shaped. Of a pinnatifid leaf, having a larger, rounded terminal lobe and successively smaller lateral lobes (Fig. 18).

main florescence   see florescence.

mallee   a growth form of some tree species, with a number of stems arising from a swollen base (lignotuber), as in various Eucalyptus spp.; a vegetation type dominated by such eucalypts.

marcescent   of structures (e.g. leaves) that remain on a plant after withering, not falling.

marginal   of a vein, when running more or less parallel and close to the edge of a leaf, glume, lemma etc. Of placentation, the ovules attached along one side of the ovary (Figs. 5a, 66b; Pl. 15d).

mast flowering   see gregarious flowering.

mealy   of a surface, with a whitish floury appearance or texture.

median   situated in the middle.

membranous   of the nature of plant parts (e.g. bracts), thin, soft and flexible, often more or less translucent, not green and herbaceous.

mericarp   one unit of a fruit which breaks up at maturity into segments derived from the individual carpels (Pl. 34h).

meristem   a group of undifferentiated cells capable of active division.

mesandrous   of bisexual spikes within Carex inflorescences in which male flowers are borne towards the centre and female flowers at each end. Cf. mesogynous.

mesocarp   the middle layer of a pericarp.

mesogynous   of bisexual spikes within Carex inflorescences in which female flowers are borne towards the centre and male flowers at each end. Cf. mesandrous.

mestome sheath   the inner ring of cells of a bundle sheath. Cf. parenchyma sheath.

midrib/midvein   the (usually) prominent main longitudinal vein (vascular supply), usually centrally placed, of a leaf, bract, glume or scale etc.

monadelphous   of stamens united by their filaments into one group. Cf. diadelphous.

monocarpic   of a plant that flowers and fruits only once before dying.

monochasium   an inflorescence type in which the axis ends in a flower and a subsequent flower arises from a bud behind the terminal flower. A monochasium is said to be compound if the pattern is repeated (Fig. 11).

monocot   abbreviation of monocotyledon.

monocotyledons   in classification, the major subgroup of the Flowering Plants having seeds with a single cotyledon. Formally spelled Monocotyledones, or Monocotyledoneae. (See Chapter 6.)

monoecious   of a plant or species, having unisexual flowers of both sexes (male and female) on the one plant, e.g. Zea mays (Corn). Noun monoecy, cf. dioecious.

monophyletic   of a taxonomic group when made up of all the descendants of one ancestral line. Cf. paraphyletic, polyphyletic.

monopodial   a growth form (e.g. of rhizomes or stems etc.) with a main axis whose apex continues growth, and may give rise to lateral branches. Cf. sympodial.

monospecific   of a genus that contains only one species.

monotelic   see inflorescence.

monotypic   describes a taxon that includes only one member of the rank below, e.g. a family containing only one genus, or a genus with only one species.

morphology   in general, the study of external form. In plant taxonomy, the study of external form, including shape and structure, and that of the plant’s parts.

mucilage   a slimy excretion, or this sometimes retained within the plant tissue.

mucro   a short sharp point, usually on a leaf or bract, sometimes fragile (Fig. 17). Adj. mucronate.

multiple fruit   a category of fruit types in which each fruit is the product of all the individual mature free carpels in one flower, and in this sense is synonymous with aggregate fruit, but sometimes also used as synonymous with compound fruit.

muricate   of a surface, roughened with short, firm, pointed projections.

muticous   blunt, without a point.

napiform   a three-dimensional form, resembling a turnip, i.e. broadly ovoid and tapering to the end. Most often used to describe the shape of a tap root.

native   of a plant or species (or other group) when occurring naturally in a specified region.

naturalised   of a plant or species (or other group), introduced from another region, growing and reproducing readily without assistance, and now established.

nectar   a sugary liquid often produced by flowers, or occasionally by glands elsewhere on the plant.

nectary   a gland that produces nectar.

neoteny   a condition of plants thought to show juvenile characteristics, presumed to be evidence of arrested development.

nerve   a vein, e.g. in a leaf or bract.

neuter   lacking functional reproductive organs (e.g. a grass floret). Sterile.

node   the part of a stem between two successive internodes from which a leaf and/or branch arises (Fig. 13c), or used to arise. In Grasses often distinctively coloured and noticeably different to the adjacent stem.

nut   a fruit type; often defined as a hard, dry, indehiscent, one-seeded fruit derived from a gynoecium of two or more united carpels (e.g. an acorn), although some authors have recommended discarding the term because of the considerable inconsistency with which it is applied. Sometimes used almost interchangeably with achene, one difference cited being the hardness of the pericarp.

nutlet   most often referring to a one-seeded entity produced by a fruit that fragments at maturity, e.g. especially in Lamiaceae (Mint Family) and Verbenaceae (Verbena Family), but sometimes used more loosely for any very small nut, e.g. in Cyperaceae (Sedge Family).

ob-   a prefix meaning reversed or against, often seen referring to leaf shapes (as in the next two entries) where a shape is inverted compared to the shape defined by the term without the prefix.

obcordate   a two-dimensional shape, heart-shaped and attached by the pointed end with the widest part towards the apex (Fig. 16).

oblanceolate   a two-dimensional shape (e.g. a leaf) of length about five times the width, the widest part above the centre and tapering to the base (Fig. 16).

obligate   limited to (‘obliged’ to conform to) a particular mode. Cf. facultative.

oblique   of a leaf blade, asymmetrical at the base (Fig. 17). In general, slanting.

oblong   a two-dimensional shape (e.g. a leaf) where length is two or three times the width and sides roughly parallel (Fig. 16).

obovate   a two-dimensional shape (e.g. a leaf) where length is about one and a half times the width and widest above the centre (Fig. 16).

obovoid   a three-dimensional figure, egg-shaped, with the largest diameter above the middle.

obsolescent   almost, or becoming obsolete.

obsolete   usually seen referring to structures that are reduced in size, and nonfunctional, sometimes apparently completely lacking.

obtuse   rounded or blunt (usually referring to the apex or base of a structure such as a leaf or bract, Fig. 17).

ochrea   a sheath around a stem at the base of a leaf, formed from united stipules (Fig. 15). Common in the family Polygonaceae.

ontogeny   a developmental cycle (of an organism or structure) within the current generation, e.g. within a flower, the development of a sepal or stamen from inception to fully formed.

open   of a leaf sheath, when split longitudinally down one side thus not forming a closed cylinder around a stem. Of a grass inflorescence in which the branches and spikelet stalks are rather long, widely spaced and readily visible. In this usage often as opposed to condensed or contracted.

operculum   a lid or cap, often of a flower bud (as in Eucalyptus, Figs. 85a, 87b).

opposite   of leaves, in pairs at each node, with one leaf of each pair on the opposite side of the stem to the other (Fig. 15). Of organs in a flower when on the same radius, e.g. the stamens and sepals in Figure1a.

oral setae   in bamboos, bristle-like structures arising at the apex of the leaf sheath at its junction with the pseudopetiole.

orbicular   a shape (e.g. of a leaf blade), more or less circular (Fig. 16).

organelle   a specialised part or entity within a plant cell, e.g. a chloroplast.

orifice   in general, an opening, e.g. at the apex of a leaf sheath, or of a utricle in Carex.

ornamental   used as a noun indicating a plant or species cultivated for some desirable feature.

ostiole   of a utricle in Carex (Sedge) and related genera, the apical opening through which the style is exserted.

oval   a two-dimensional shape (e.g. of a leaf), about twice as long as wide, rounded at both ends (Fig. 16). Somewhat broader than elliptical.

ovary   the hollow portion at the base of a carpel (or of united carpels) containing one or more ovules (e.g. Figs. 1, 4, 5d; Pls. 2e, 4i, j).

ovate   a two-dimensional shape (e.g. of a leaf) wheref length is about one and a half times the width, widest below the centre (Fig. 16). Egg-shaped in outline.

ovoid   egg-shaped, i.e. a solid that has an ovate longitudinal silhouette.

ovules   structures found in the ovary which enclose the egg-cells and become seeds after fertilisation and subsequent development (Fig. 4).

pachymorph   of the rhizomes of some species of bamboos, short and thickened (at least in part), and soon terminating in an upright culm, sympodial. Species with this rhizome form are commonly called ‘clumping bamboos’ in horticultural contexts. Adj. pachymorphic, cf. leptomorph.

paired   of a structure when occurring in twos, i.e. in pairs.

palea   in Asteraceae (Daisy Family), a small scale subtending a floret within the flowerhead (Pl. 33b), also referred to as a receptacle scale. In Poaceae (Grass Family), the inner and (usually) smaller of the two bracts enclosing a typical flower, usually two-nerved and two-keeled (Fig. 39), sometimes absent.

paleae (plur.)   in Asteraceae (Daisy Family) refers to scales between (subtending) florets on the receptacle, which may then be described as paleate (Pl. 33b).

palmate   of a leaf, with five or more leaflets (or lobes according to some authors) spreading from the same point, somewhat like the fingers of a hand (Fig. 14g). May also describe leaf blade venation when spreading from the top of the pedicel.

palmatifid   of a deeply dissected leaf (but sometimes defined as cut less than halfway to the centreline) in which the resulting lobes spread like the fingers of a hand (Fig. 18). Palmatisect is similar but is more deeply cut, possibly almost to the centreline.

panicle   an inflorescence type which, as often used, is simply much-branched with the individual flowers stalked. Adj. paniculate. Some authors specify that the main axis and the lateral branches are indeterminate (Fig. 10c), thus the panicle could be thought of as a compound raceme. Other authors require the main and lateral axes to be determinate. The adjectival forms paniculate and paniculiform are sometimes used in the sense of ‘panicle-like’. In grasses, the panicle is usually accepted as a much-branched inflorescence with stalked spikelets. In the grass tribe Andropogoneae, some branched inflorescences bear bracts that subtend branches, or inflorescence units, made up of (usually) jointed racemes. These inflorescences are sometimes called false panicles.

papillae   small rounded (pimple-like or nipple-like) projections. Adj. papillose.

pappus   in the florets of most daisies, the hairs, bristles or scales (usually forming a ring) found at the base of the corolla, sometimes interpreted as a modified calyx (Figs. 117b, 118d, 124c; Pls. 32e, k, 33d, e). In certain grasses whose fruits appear geared to wind dispersal, long hairs borne on the upper part of the lemma.

paraclade/paracladium in general of a compound inflorescence, lateral branches that repeat the same pattern shown by the upper part of the main axis (that part above the lateral branches). See entry under inflorescence.

paraphyletic   of a taxonomic group that includes some (or most) but not all of the descendants of their common ancestor. Cf. monophyletic, polyphyletic.

parasite   a plant living on another plant, the host, and drawing food from it.

parenchyma   living, mature cells, generally with thin walls, forming relatively unspecialised plant tissue. Adj. parenchymatous.

parenchyma sheath   the outer ring of cells of a bundle sheath. Cf. mestome sheath.

parietal   of placentas, attached to the inside of the outer wall of the loculus (Figs. 5g, 131c; Pl. 4d, k).

paripinnate   of a pinnate leaf, having an even number of pinnae including a pair in the terminal position (Fig. 14i).

partite   divided into parts, e.g. a five-partite corolla has five petals.

patent   of branches etc., widely spreading (more or less at right angles) from the parent axis.

pectinate   usually of a margin, comb-like, i.e. with narrow, closely placed projections resembling the teeth of a comb.

pedicel   the stalk of an individual flower (solitary or within an inflorescence). In grasses, sedges and some Restionaceae, the stalk of a spikelet. Adj. pedicellate.

peduncle   in general, the stalk of an inflorescence of more than one flower (Fig. 10d, f) but a rather imprecise term. In grasses sometimes the stalk of part of an inflorescence. In sedges e.g. the stalk of the individual spikes in some Carex inflorescences, or the common stalk of a group of spikelets. Adj. pedunculate.

pellucid   in general, translucent (i.e. partially or incompletely transparent), often describing small spots on a leaf surface, perhaps glands or oil cavitites.

peltate   of a leaf or other organ that has the stalk attached to the middle of the lower surface (Figs. 17, 95a).

pendulous (also pendent)   in general, of a structure when hanging downwards, often because the stalk has bent. Of an ovule, attached at or near the top of the ovary (Fig. 5b). Of an anther when hanging from the filament (Fig. 3d).

penicillate   of a structure (e.g. an anther) tipped with a tuft of hairs.

pepo   an indehiscent fruit type formed from an inferior ovary often with parietal placentation, and containing many seeds. The fruit is usually large with a tough outer skin and pulpy interior, typical of Curcurbitaceae, e.g. pumpkin, cucumber.

perennating   of an organ that survives vegetatively from season to season. A period of reduced activity between seasons is usual.

perennial (noun or adj.)   a plant with a normal life span of more than two years or two growing seasons.

perfect   of a flower, with both male and female organs present and functional.

perfoliate   of a leaf base that completely surrounds the stem, so the stem appears to pass through the leaf blade (Fig. 15).

perianth   the outer non-reproductive part of the flower, usually consisting of a whorl of sepals and/or a whorl of petals, or two whorls of tepals (Fig. 1b).

pericarp   the fruit wall, developed from the ovary wall.

pericarpium   a ripened ovary without any accessory structures or associated parts such as awns, bracts, perianth, swollen receptacle etc. Cf. anthocarp.

perigon/perigone/perigonium   a general term for the perianth, usually when the sepals and petals are not clearly differentiated as in many Monocots. E.g. in species with lily-like flowers sometimes used to indicate the postition of nectariferous tissue (perigonal nectaries). In Sedges sometimes used to refer to hypogynous bristles. In Typha (Bulrush) sometimes used to refer to the hairs on the stalk below the ovary (perigone hairs).

perigynium   in general, a structure surrounding the gynoecium. The term has been used to refer to a floral tube, e.g. in Myrtaceae (Myrtle and Eucalypt Family) where the floral tube is usually fused to part or all of the ovary wall. Or commonly used for the enclosing structure around the gynoecium in Carex (Sedge) and related genera, then often also called a utricle.

perigynous   of a flower, with a cup-shaped floral tube around the superior ovary, the perianth parts and stamens attached to the rim of the cup (Fig. 8c; Pl. 3e).

persistent   remaining attached, not falling, e.g. of the bark of certain trees, or the staminal filaments in the flowers of some sedges, etc.

petal   a member of the corolla, the inner whorl of perianth parts (Fig. 1b).

petaloid   like a petal, usually colourful and showy.

petiole   the stalk of a leaf (Fig. 14a). Adj. petiolate.

petiolule   the stalk of a leaflet.

phloem   a component of the vascular tissue of plants—groups of cells involved in the conduction of the products of photosynthesis.

photosynthesis   the process by which carbohydrates are made from carbon dioxide and water in cells containing chloroplasts. The chemical energy required is produced from solar energy in the presence of the pigment chlorophyll.

phyllary   a bract in an involucre, mostly seen in reference to daisies.

phyllode   a leaf-like organ derived from the petiole; the foliage of many Acacia (Wattle) spp. is of phyllodes (Figs. 58–61; Pl. 14f, h–j).

phyllopodic   of a fertile shoot when the lower leaves bear normal blades, e.g. in many Carex (Sedge) species that have remnants of last season’s leaf blades at the base of the fertile culms. Cf. aphyllopodic.

phylogeny   the evolutionary relationships among organisms. Present-day relationships are viewed as the consequences of evolutionary history.

phytomelan   a charcoal-like substance causing the seed-coats of some plant species to appear black. Given significance in classification by some authors.

phytomere   in grasses, a structural unit made up of an internode with a bud at its base and a leaf at its apex. Part of a morphological concept that sees the plant made up of a number of such units according to the habit of the species.

pilose   of a surface, with soft, reasonably long hairs but usually not dense.

pinna (plur. pinnae)   a leaflet of a pinnate leaf, or the equivalent part of a bipinnate leaf (Fig. 14d, e).

pinnate   of a compound leaf, having a row of leaflets on each side of the rachis (Fig. 14d, h, i).

pinnatifid   a shape (e.g. of a leaf), when pinnately lobed with the blade cut about half way to the midrib (Fig. 18).

pinnatisect   a shape (e.g. of a leaf), when pinnately lobed with the blade cut almost to the midrib (Fig. 18).

pinnule   a segment formed by the pinnate division of a pinna (Fig. 14e).

pistil   the functional seed-producing unit of a flower. Thus, depending on the context, the term could refer to an individual carpel (if a flower has only one, or several free carpels) or to a gynoecium of several united carpels (when better regarded as a compound pistil). Almost universally taken to be the ‘female’ part of the flower but see the note under gynoecium.

pistillate   of a flower or floret, with fertile carpel(s) but no functional stamens. A pistillate scale subtends such a flower. Cf. staminate. Often assumed synonymous with ‘female’, but see note under gynoecium.

pistillode   a sterile pistil.

pith   usually the centrally placed ground tissue within stems and roots, and consisting of parenchyma cells, often spongy.

placenta   the tissue within the ovary to which the ovules are attached (Fig. 4a).

placentation   the arrangement of placentas within the ovary (Fig. 5). A number of different types are recognised depending on the placement of the placental tissue.

planoconvex   describes a three-dimensional structure (e.g. a leaf blade of some sedges) when flat on one side and rounded (convex) on the other.

plantlet   a very small plant. Grass and sedge spikelets sometimes become modified into tiny plantlets forming a means of vegetative reproduction.

plesiomorphy   a character believed to be ancestral (e.g. a plant feature believed be little changed through evolutionary time), and not now restricted to any particular group. Cf. apomorphy. Adj. plesiomorphic.

plicate   pleated, i.e. folded longitudinally a number of times like a hand-held fan.

plumbeous   in colour, leaden grey.

plumose   feather-like (as in down feathers), or plume-like. Often said of fine bristles which are themselves clothed in rather long hairs (Pl. 32k).

plumule   the young, as yet undeveloped, shoot of an embryo.

pluricaespitose   of the habit of certain bamboos, culms arising in a series of clusters along a long slender rhizome.

pollen   the collective name for the grains that develop within an anther. The pollen grains contain the male reproductive nuclei.

pollination   the transfer and receipt of compatible pollen from an anther to a stigma.

pollinium   a mass of pollen enclosed by a membrane, or held together by a sticky substance (Fig. 26b). During pollination, a pollinium may be transferred as a unit.

polygamous   of a species or plant, bearing both bisexual and unisexual flowers on the same plant. Some authors extend the definition to include species or plants with the different flower types on different plants.

polymorphic   of a species or plant part or structure, having different forms, variable.

polyphyletic   of a taxonomic group when including members with differing ancestry, i.e. a group not restricted to the descendents of one evolutionary lineage. Cf. monophyletic, paraphyletic.

polyploid   of a species or plant, with each cell nucleus having more than two of the basic sets of chromosomes. The term includes such cases as triploid, tetraploid and hexaploid (with 3, 4 and 6 sets of chromosomes respectively).

polytelic   of an inflorescence, with an indeterminate main axis and lateral branches. See notes under inflorescence.

pome   an indehiscent fruit type in which the fleshy layer has developed partly from the ovary wall but mostly from the floral tube, e.g. apple.

poricidal   of dehiscence, when contents are shed through pores, as in the poricidal capsule of a poppy (Pl. 4e).

posterior   of orientation, in general, towards the back. Of a flower, the side adjacent to the axis.

prickle   a hard pointed appendage without vascular tissue.

procumbent   of plant habit, with stems that lie more or less along the ground, and sometimes specified that roots are not produced at the nodes.

proliferous   of inflorescences or leaves etc., bearing vegetative buds or plantlets capable of detaching and forming separate plants. In some grasses the spikelets in an inflorescence may be modified as small plantlets.

prolonged   in general, an extension of a structure, e.g. of a rachilla in a spikelet when extended beyond the uppermost floret.

propagule   a structure capable of giving rise to a new plant. The term could include seed, spores, etc. although some authors restrict it to refer to vegetative propagation, e.g. via a rhizome fragment.

prophyll   in general, the first, usually reduced, leaf of a lateral shoot. Usually single in Monocotyledons and situated on the adaxial side of the shoot (then sometimes referred to as an addorsed prophyll), and paired in ‘Dicotyledons’ with one on each side of the shoot (transverse). In Carex (Sedge) and related genera the perigynium/utricle is usually interpreted as a modified prophyll (i.e. the first ‘leaf’ of the lateral flowering shoot that bears the female flower).

prop roots   adventitious roots (Fig. 120) that develop from the lower nodes of a stem and help to support it. Often well developed in large grasses such as Zea mays (Sweet Corn, Maize).

prostrate   of stems, or describing plant habit, when lying flat on the ground.

protandrous   of a flower (or species bearing such flowers) whose anthers shed their pollen before the stigma(s) of the same flower are receptive. Cf. protogynous.

protogynous   of a flower (or species bearing such flowers) in which the stigma is receptive before the anthers of that flower release their pollen. Cf protandrous.

proximal   situated at or near the attached end of a structure, as opposed to the free (distal) end.

pruinose   of a surface, with a waxy covering (a ‘bloom’, usually whitish).

pseudanthium   in general, an inflorescence that resembles a single flower, e.g. the flowerheads of many daisies. The individual ‘true’ flowers are usually small and to some degree reduced (sometimes drastically so).

pseudobulb   generally a part of a stem that is modified, often swollen, for storage of water and nutrients, e.g. as seen in many orchids.

pseudoculm   of some Carex (Sedge) spp., the more or less firm, stem-like structure formed only of overlapping leaf sheaths. Cf. vegetative culm.

pseudolateral   of an inflorescence, appearing to emerge from the side of a stem but in fact terminal with a bract continuing the appearance of the stem above the the inflorescence, e.g. in some Juncus (Rush) spp.

pseudomonomerous   of a gynoecium, appearing to be made up of a single carpele carpel but technically of several united carpels, the evidence for carpel number obscuredr obscured.

pseudopetiole   of a grass leaf blade, a narrower basal part that resembles the true petiole found in most eudicotyledon leaves. Commonly seen in bamboos. Adj. pseudopetiolate.

pseudospikelet   in some bamboos, a false spikelet in which the lower glumes or bracts subtend buds that can develop to form further spikelets (that may repeat the process, in time giving rise to a dense cluster). In some sedges, e.g. Chorizandra (Bristle-rush) a structure resembling the spikelets of other sedges but differing in its arrangement of flowers and glumes.

pubescent   covered with short, fine, erect, often dense, hairs. Dim. puberulent.

pulvinus (plur. pulvini)   a small swelling at the base of a petiole or leaflet, sometimes glandular, allowing some movement e.g. in response to stimuli such as heat or touch. Commonly seen at the bases of phyllodes in Acacia (Wattle) species (e.g. Figs. 61, 62). In grass inflorescences such as panicles, often found at the bases of branches facilitating the opening and closing of the inflorescence. In sedges, sometimes seen at the base of a spikelet.

punctate   of a surface, dotted, e.g. of leaf blades when often caused by small translucent glands. Dim. puncticulate.

pungent   having a firm sharp point. (In botanical contexts, not related to odour.)

pyriform   pear-shaped.

raceme   an inflorescence type, commonly defined as stalked flowers borne on an elongated, unbranched axis with the youngest flowers at the apex (Fig. 10b). Adj. racemose. While generally considered an indeterminate type (then sometimes called a botrys or botryum), some authors include the possibility of a raceme ultimately ending in a flower (then a botryoid). The adjectival form racemiform may be used in the sense of ‘raceme-like’. In grasses, an unbranched axis supporting stalked spikelets. If the spikelet stalks are very short, some authors simply refer to the inflorescence as a spike, thus blurring the boundary between the definitions of a spike and a (spike-like) raceme.

racemose   as usually defined, denotes the branching pattern of a number of inflorescence types in which the main axis continues growth for an indefinite time, producing lateral buds which will grow out as flowers or branches that may repeat the same pattern (Fig. 10). Cf. cymose. Some authors exclude the requirement for an indeterminate axis and instead base their definition on the (theoretically) unlimited number of lateral axes from the main axis.

rachilla   in general, a small axis In grasses and sedges and some members of the family Restionaceae, the axis of a spikelet (Fig. 38e). In plants with bipinnate leaves, the axis of a (divided) pinna (Fig. 14e). Sometimes spelled rhachilla.

rachis (plur. rachises/rachides)   the main axis of an inflorescence. In grasses restricted by some authors to the axis of a raceme or spike. In a pinnate leaf, the axis that bears the leaflets (Fig. 14d). Sometimes spelled rhachis.

radial   with respect to floral symmetry, sometimes used as an alternative to actinomorphic (q.v.).

radiate   in general, of structures spreading from a common point. Of a capitulum (e.g. in the Daisy Family), with ray florets surrounding disc florets (Fig. 118a; Pls. 32b, c, 33a, g, j).

radical   of leaves, arising from near the base of the plant (Fig. 15).

radicle   the rudimentary root of an embryo within a seed.

radioli   in some sedges, the ultimate branches (rays) of a compound inflorescence that bear the spikelets (the term used especially in conjunction with the large anthelate inflorescences of some Cyperus spp.).

rambler   a plant, lacking erect stems, which spreads along the ground or over other plants, fences etc.

rame   in the inflorescences of certain grasses (particularly in the tribe Andropogoneae), a jointed branch that breaks up into dispersal units at maturity. Each unit is commonly a pair of spikelets, one spikelet sessile, the other stalked. In older texts these types of branches are usually referred to as racemes.

rank   any level in a classification scheme. Thus family, genus and species are all ranks at different levels, with family being of ‘higher’ rank than genus, which in turn is higher than species. In plant structure, of parts arranged in vertical rows, as in ‘leaves three-ranked’.

ray   a main branch of an umbellate inflorescence.

ray floret   one of the ligulate florets around the edge of a capitulum, as in many daisies (Fig. 116).

receptacle   the end of the flower stalk to which the flower parts are joined (Fig. 1), considered by some authors to include the floral tube, if present. In species with flowers in heads such as in Asteraceae (Daisy Family), the more or less expanded end of the inflorescence stalk that bears the individual florets (Figs. 118b, 122c).

recurved   curved under, e.g. of leaf margins (Fig. 17).

reduced   of spikelets or florets (or other structures), not fully developed, i.e. with parts missing or smaller in size, not fertile, not producing seed.

reflexed   bent abruptly backwards from the axis or point of attachment forming a small angle to the axis. Some authors include ‘bent abruptly downwards’ within the definition.

regular   see actinomorphic.

remote   of two or more structures when well separated or distant from each other, e.g. the branches within an inflorescence.

renascent   of a plant or species that dies down each year to an underground organ.

reniform   kidney-shaped, often referring to leaves (Fig. 16).

repent   of a prostrate plant that roots at the nodes of the spreading stems. Creeping.

replum   within an ovary with parietal placentas, a longitudinal ridge or flange growing out and eventually forming a false septum, e.g. in the fruits of many Brassicaceae (Cabbage Family), the replum remaining after the valves and seeds have fallen (Pl. 23g). Some authors restrict the term to just the marginal ridge, others include the false septum. May also refer to the sutures remaining from a leguminous fruit after the rest is shed or breaks apart (see craspedium).

resupinate   of an organ when rotated through 180 degrees, e.g. a flower that appears upside down through rotation of the pedicel or ovary, as occurs in some orchids.

reticulate   net-like.

retrorse   usually of hairs or other surface projections, directed away from the apex of the organ that bears them. Cf antrorse.

retuse   with a central notch in a bluntly rounded apex (Fig. 17). Some authors specify a rounded indentation or notch, as opposed to emarginate with a sharp notch.

revolute   rolled under, e.g. of leaf margins (Fig. 17).

rhachides   raceme axes (see rachis).

rhachilla   see rachilla.

rhachis   see rachis.

rhipidium   a type of monochasial inflorescence in which the flowers lie in one plane on alternate sides of a zigzag axis, e.g. seen in the Iridaceae (Iris Family).

rhizanthogene   in some grasses, a modified spikelet borne on a rhizome.

rhizome   an underground stem, usually more or less horizontal, often containing food reserves, the nodes often bearing scale leaves and producing roots and/or shoots. Adj. rhizomic, rhizomatous.

rhombic   a shape, e.g. of a leaf, that is roughly diamond-shaped and length more or less equals width (Fig. 16).

rhomboid   a four-sided shape, with opposite sides parallel, and adjacent sides of unequal length (an oblique rectangle), or sometimes defined as kite-shaped.

ribbed   of a surface (e.g. of a leaf, bract, stem etc.) with rather prominent longitudinal raised lines (often formed by the veins).

riparian   of a plant, or species or vegetation type etc., growing on the margins of a stream or river.

root cap   a cap of cells that protects the end of a root as it grows through the soil.

root hairs   outgrowths of the outermost layer of cells just behind the root tip, functioning as water-absorbing organs.

rootstock   of a herbaceous plant, a region at the junction of the root system and above-ground stem(s). In horticulture, the lower part (root system and lower stem) of a young plant onto which part of another plant (usually stem or bud material) is grafted.

rosette   leaves radiating from a centre, usually basal (Pl. 32f).

rostellum   in some orchid flowers, an outgrowth or ridge derived from part of the third stigma lobe, between the stigma and anther (e.g. Fig. 26b).

rosulate   with a basal rosette.

rotate   of a corolla, with a short tube and spreading limb (Fig. 2h), wheel-shaped.

ruderal   of a plant or species etc., growing in waste ground or disturbed sites.

rudimentary   of an organ that is incompletely developed.

rugose   of a surface, wrinkled and usually rough. Dim. rugulose.

runcinate   of a lobed leaf, with the ends of the lobes pointing down towards the petiole (Fig. 18).

saccate   pouched.

sagittate   shaped like an arrow-head with basal lobes pointing downwards (Fig. 16).

salver-shaped   of a tubular corolla, with lobes that spread more or less horizontally, as in Phlox. Also sometimes seen as salveriform.

samara   a dry, indehiscent, one-seeded fruit with part of the wall extended to form a wing, e.g. fruits of Fraxinus (Ash) and Acer (Sycamore).

saprophyte   a plant living on, and absorbing its food from, dead organic matter, and usually not carrying out photosynthesis.

scabrid   see scabrous.

scabrous /scabrid   of a surface, covered by small rough projections or small stiff hairs, thus rough to the touch.

scale   often used instead of ‘bract’ for small, thin, leaf-like appendages. Also refers to the units (hypogynous scales) representing a perianth in certain sedges.

scandent   climbing.

scape   the flowering stem of an otherwise stemless plant, e.g. Dandelion. Adj. scapose. Sometimes extended to include the flowering stems of e.g. Xanthorrhoea (Grass-tree) that may have a lower stem below the insertion of the leaves.

scarious   thin and dry, often almost transparent, not green. Often used to describe such margins of otherwise herbaceous bracts.

schizocarp   a dry fruit derived from a syncarpous ovary and splitting at maturity into one-seeded segments.

sclerenchyma   a supporting and/or protective tissue made up of thick-walled cells, often lignified.

scorpioid cyme   see cincinnus.

secondary thickening   the formation of additional tissues in the stems of some plants through the activity of a cylindrical meristem (the cambium) just under the bark, e.g. giving rise to increasing girth in the trunks of trees.

secund   with the lateral members all turned or directed to one side (often describing one-sided inflorescences).

seed   the usual reproductive unit of Flowering Plants, the product of a fertilised ovule and containing an embryo with food reserves. In reference to grasses, sometimes used loosely referring to what is correctly the fruit.

seed leaf   a cotyledon, a leaf-like organ within the seed.

self-compatible   self-fertile, i.e. a flower’s own pollen will fertilise its ovules.

self-incompatible   self-infertile, i.e. a flower’s own pollen will not fertilise its ovules.

self-pollination   also called selfing, the acceptance by stigmas of pollen from the same flower or from flowers on the same plant, which means they are self-compatible.

semelauctant   of the inflorescences of some bamboos with spikelets that do not have buds in the axils of basal bracts. Can be roughly understood as ‘once growing’ or ‘once increasing’. Cf iterauctant.

sepal   a unit of the calyx or outer perianth whorl, often green in colour (Fig. 1).

sepaline   resembling a sepal, of the sepals.

sepaloid   resembling a sepal.

septate-nodulose   externally roughened by minute lumps as a consequence of internal partitions. Often more apparent when the plant material is dried.

septicidal   of dehiscence in which a fruit (e.g. a capsule) splits along longitudinal lines coinciding with the internal septa, each valve then made up of the outer wall of one carpel. Cf. loculicidal.

septum (plur. septa)   in general, an internal dividing wall. In floral structure, the wall(s) dividing an ovary into two or more loculi (Figs. 30c, 31c; Pls. 5f, 9d) Adj. septate, divided by partitions.

sericeous   of a surface when covered with soft, more or less glossy, appressed hairs giving a silky sheen.

serrate   of a margin (e.g. of a leaf) regularly toothed, with the individual teeth directed more or less towards the leaf apex (Fig. 18). Dim. serrulate, finely serrate.

sessile   without a stalk, most often of leaves or flowers; in grasses and sedges, commonly of spikelets.

seta (plur. setae)   a bristle or stiff hair. Adj. setaceous, resembling a bristle, sometimes referring to leaf blades that are fine, stiff, and narrowly cylindrical.

setiform   bristle-shaped, resembling a seta.

sheath   in general, a tubular structure that encloses another part, most often of a leaf base that forms a tubular casing around the stem.

shoot   usually applied to a young, developing plant axis with its associated leaves etc., e.g. the initial stem arising from a germinating seed, or young lateral branches arising from a mature stem.

shoulder   in some bamboos, upper parts of the culm sheaths which are wider than, and narrow abruptly into, the blade, thus forming the ‘shoulders’.

shrub   generally a perennial woody plant, self-supporting but usually with no single main axis, which branches freely (usually close to the ground) and does not exceed about 5 m (approx.) in height. A descriptive term not really amenable to strict definition.

silicula   similar to a siliqua (q.v.) but the length of the fruit is less than three times its width.

siliqua/silique   a dry dehiscent fruit, of length more than three times the width, formed from two united carpels, with the superior ovary having two parietal placentas and divided into two sections by a thin partition (a false septum), opening from the bottom upwards by two valves, e.g. in Brassicaceae (Cabbage Family, Pl. 23g). Cf. silicula.

silk   of the grass Zea mays (Corn, Maize), the stigmas collectively.

simple   in general with respect to structure, undivided. Of leaves, with the blade undivided (but the margin may be dissected). Of inflorescences with only one order of branching.

sinuate/sinuous   of a margin (e.g. a leaf blade) when shallowly, smoothly and regularly indented in the same plane as the blade (Fig. 18). Wavy. Of an axis regularly bent one way then the other in a smooth or shallow manner.

sinus   in general, a notch or indentation in a margin. Of a grass glume or lemma with a notched apex, the sinus is the ‘valley’ or notch between the two lateral lobes.

solitary   in general, single. Of flowers that grow one per plant, or one in each leaf axil, or individually and widely separated on the plant.

spadix (plur. spadices)   an inflorescence type, a spike of flowers on a fleshy axis, the spike usually subtended by a large bract called a spathe, e.g. Arum Lily (Pl. 8d).

spathe   a large bract enclosing a spadix, e.g. the white part of an Arum Lily ‘flower’ (Pl. 8d). Also used with reference to bracts subtending the inflorescence in some other Monocotyledon families, e.g. in the grass tribe Andropogoneae used for a bract subtending and often (at least partly) enclosing an inflorescence branch, or in the Restionaceae used for a primary subtending inflorescence bract. Adj. spatheate, dim. spatheole.

spathella (plur. spathellae)   a term sometimes used as an alternative to spatheole (see spathe).

spathulate   spoon-shaped, or shaped like a spatula. Sometimes spelled spatulate.

species   the basic unit in classification (see Chapter 3) and generally thought of as a ‘kind’ of organism. Cited characteristics of a species usually include: being made up of a number of individuals of closely similar morphology, possession of a number of constant distinguishing features, and the capacity to readily interbreed in nature to produce fertile offspring. Nature does not always comply in every respect with science’s definitions.

species aggregate   refers to a group of closely related entities, usually with very similar morphology and not easily distinguished, which are treated for the time being or for practical purposes as a single species.

specific epithet   the second word in the two-part scientific name of an organism. Also trivial name.

spicate   spike-like.

spiciform   of an inflorescence (often a panicle), having the form of or resembling a spike, much longer than wide and densely compact.

spicoid   the ultimate flowering unit in Cyperaceae subfamily Mapanioideae (tribes Chrysitricheae and Hypolytreae) consisting of an axis ending in a gynoecium and bearing numerous proximal glumes/scales most of which subtend a stamen.

spicoid bract   a glume-like bract which subtends a spicoid in some sedges.

spike   an inflorescence (or part thereof) with sessile flowers on an elongated, unbranched axis (Fig. 10a). In the Grass Family, an elongated, unbranched axis with sessile spikelets (thus the whole, or part, of an inflorescence could be a spike), although some authors allow spikelets to be subsessile undermining any clear division between a spike and a spike-like raceme. In the Sedge Family, commonly an unbranched axis bearing spikelets, often forming part of an inflorescence. Loosely used for the main unit of the inflorescence in Carex spp.

spikelet   in essence a ‘very small spike’, i.e. a short axis bearing sessile flowers with their subtending bracts. The basic unit of the inflorescence in the Grass Family, composed of a short axis, the rachilla, bearing two empty basal glumes, and one or more florets each made up of two bracts (the lemma and palea) and enclosed flower (Figs. 38d, 40c; Pl. 13a, b, d). Also the basic unit of the inflorescence of many Sedges and Restios but the spikelets in these families differ in structure and are not considered botanically equivalent to those of Grasses.

spine   usually defined as a modified leaf or stipule (or sometimes including a modified branch) that has become hard and pointed, and generally assumed to include continuity of vascular tissue. Sometimes used more loosely to describe other stiff pointed outgrowths.

spinulose   bearing small spines.

spur   a short shoot. Also a conical or tubular outgrowth (usually hollow) from the base of a perianth segment, often containing nectar.

squamose   of a surface, covered with small scales, these usually overlapping (e.g. Fig. 95). Dim. squamulose.

squarrose   with bracts, glumes, scales etc. (or just their tips) spreading outwards from the axis. In some Sedges, refers to the apex of the glumes in the spikelets.

stamen   a unit of the outer whorl of reproductive organs within a bisexual flower, usually consisting of a stalk (the filament) and a bilobed anther which contains pollen (Figs. 1, 3). See also androecium.

staminate   of a flower or floret, with fertile stamens but no functional carpels. Cf. pistillate. Often assumed synonymous with ‘male’, but see note under androecium. Also used to specify a bract subtending stamens, as in ‘staminate scale’.

staminode   a sterile stamen, usually of modified (often reduced) structure (Fig. 3l).

standard   the petal that stands at the back of the flower in the subfamily Papilionoideae (Peas), usually larger than the other four petals. Sometimes also called the ‘banner’ (e.g. Figs. 65, 66).

stellate   star-like or star-shaped; often used to describe a tuft of hairs arising from a central point, or hairs with a number of branches arising from a central point. Stellate indumentum, a covering of such hairs.

stem   the plant axis, either aerial or subterranean, which may bear leaves, branches, and flowers.

sterile   generally of reproductive structures, infertile. Of plants not producing seeds, of stamens not producing pollen, of flowers without an ovary, etc.

stigma   the receptive surface on the gynoecium on which compatible pollen can germinate, often papillose and sticky (Figs. 1b, 4a). It may be directly on the ovary (Pl. 4c), or often on the apex of the style (Pl. 3e), or on branches of the style.

stipe   in general, a stalk, often small, e.g. used in reference to a stalk at the base of the utricle of some Carex (Sedge) spp. Adj. stipitate.

stipel (plur. stipellae)   one of two small leaf-like or bract-like appendages at the base of the leaflets of some compound leaves. Adj. stipellate.

stipitate   with a stalk (see stipe).

stipule   one of a pair of (usually small) bract-like appendages found at the base of some petioles (Fig.14a). Adj. stipulate. Very common in the Leguminosae (Pea Family, e.g. Fig. 64; Pl. 16d, h) and Rosaceae (Rose Family, Fig. 70a).

stolon   as generally used, a horizontal stem growing over the ground that may produce scale leaves or more developed leaves, and/or roots and/or shoots from the nodes. A characteristic of some common grasses. Often distinguished from the rhizome simply by being above the ground, however in the Cyperaceae (Sedge Family) the term stolon may be used for a thin underground horizontal stem that ends in a tuber or aerial shoot. Adj. stoloniferous.

stomata/stomates (sing. stoma or stomate)   the pores in the outer cell layer of plants, facilitating gas exchange. Most prevalent on leaves, but also found on the stems of many grass-like plants.

stooling   of a tufted grass clump in which the culms towards the outside of the plant are decumbent and spreading at the base or arise below ground level.

strain   usually refers to a line of individuals of a given species (often a grass) differentiated from the remainder by some (usually superior) features. The development of a particular strain is often as a consequence of artificial breeding.

stramineous   straw-coloured.

striate   marked with fine longitudinal lines or ridges. Dim. striolate.

strict   of plant habit, upright, straight and more or less rigid.

strigose   of a surface when covered with stiff, appressed, usually more or less parallel hairs.

style   the section of a carpel or syncarpous gynoecium between the ovary and the stigma(s) (e.g. Figs. 1b, 5d; Pl. 3e). The style is usually at the top of the ovary, but may arise elsewhere, and is absent in some species in which case the stigma is borne directly on the ovary (Pl. 4a).

style-base   commonly in the Cyperaceae (Sedge Family), a more or less distinctive part of the base of the style which in some genera is persistent on the mature fruit.

stylopodium   in the Apiaceae (Celery and Carrot Family), a nectar-secreting disc and enlarged base of the styles, found on top of the ovary.

subshrub   generally, a (very) small shrub; sometimes defined as more or less woody at the base and with (partially) herbaceous stems.

subsessile   with a very short stalk, almost stalkless. Cf. sessile.

subspecies   in classification, a rank below species but above variety. Within a species, the subspecies are generally distinguished by fewer or less clear-cut features than would separate species, and populations of different subspecies are often geographically or ecologically isolated.

subtend   to stand beneath and close to, or immediately precede on the same axis, as in a bract at the base of a flower, or a leaf subtending a bud in its axil.

subulate   awl-shaped, i.e. tapering from the base to a fine point, the cross-section circular.

succulent   as an adjective, fleshy, often juicy when squashed, usually describing leaves or stems. As a noun, a plant with thick, fleshy and swollen stems and/or leaves, adapted to dry environments.

sulcate   longitudinally grooved or furrowed.

superior   of an ovary, with the perianth parts and stamens, or their united bases, arising below it (Fig. 8a, c; Pls 1–4). Hypogynous and perigynous flowers have superior ovaries. Cf. inferior.

surculus (plur. surculi)   occasionally used in descriptions of certain sedges (of tufted habit) for a short extravaginal lateral shoot from the base, initially covered in scale leaves, soon turning upwards forming a new tuft. In many texts this structure would be included within the definition of a rhizome. From the Latin for a shoot or sprout.

suture   a seam or line along which two edges are joined. A line along which a fruit may split open.

sward   a growth habit, generally of grass-like plants that form a continuous lawnlike cover.

sympatric   of species or other taxa, occurring in similar geographic areas, i.e. their distributions overlap. Cf. allopatric.

sympetalous   of a flower or species, with petals united.

sympodial   of growth (e.g. of rhizomes or stems etc.) where the main axis is soon terminated, and growth is taken up by a lateral branch, the process repeating. The resulting ‘compound axis’ is thus not the product of one growing point but of several successive growing points and their axes. Cf. monopodial.

synandrous   of stamens, united.

synapomorphy   a plant characteristic that is considered advanced or derived in an evolutionary sense and is present in all members of a group. A ‘shared, derived character’. Adj. synapomorphic.

syncarpous   of a gynoecium, made up of united carpels.

synflorescence   in general, a compound inflorescence. Within recent inflorescence terminology, this term can be defined as a ‘system of a main florescence and coflorescences’ or a ‘system of a terminal flower and paracladia’. See also inflorescence.

syngenesious   of stamens that are united by their anthers, e.g. in members of the Daisy Family to form a tube around the style (Fig. 117d; Pl. 32e, i).

synonym   in botanical nomenclature, a name, other than the one current and correct name, known to apply to a particular taxon. In some cases a synonym may become a correct name, for example if a different classification is adopted.

systematics   a field of scientific enquiry primarily concerned with investigation of the different kinds and diversity of organisms, and their evolutionary relationships.

tailed   usually of anther lobes, also of seeds, having a relatively long slender basal appendage (Fig. 123c).

tap root system   a root system with a prominent main root and smaller lateral or branch roots.

tassel   in the grass Zea mays (Corn), the male inflorescence.

taxon (plur. taxa)   a general term for a taxonomic group. Any rank in classification can be referred to as a taxon. Thus species, genera, tribes and families are all taxa of different rank. A particular species or genus etc. could be referred to in a general way as a taxon.

taxonomy   a field of scientific enquiry involving the delimitation, description, naming and classification of organisms. An aspect of systematics.

teeth   usually small, usually pointed projections, often from a margin or apex. The term is not particularly specific, and seldom used in the singular.

tendril   an organ, often a modified leaf or stem, that can coil around external supports enabling a plant to climb (Fig. 64; Pl. 8j).

tepal   a perianth segment when the perianth is not clearly differentiated into calyx and corolla.

terete   in general, cylindrical, i.e. elongated, and circular in cross-section. May be imperfectly cylindrical as the structure may taper to some degree.

terminal   situated at the tip. Of an inflorescence when borne at the end of an axis.

ternate   in general, arranged or divided into threes; describes a ‘trifoliolate’ leaf in which each leaflet is divided into three.

tessellate   in general, of a surface when marked with a tile-like pattern of squares or rectangles. Of leaf venation in some bamboos, with numerous cross veins between the longitudinal veins. Of the bark of some eucalypts when persistent and marked with numerous longitudinal and more or less horizontal furrows.

testa   the protective outer coat of a seed.

tetrad   of pollen, a group of four grains that adhere together and are released from the anther as a unit.

tetraploid   see polyploid.

thalamus   the receptacle of a flower, sometimes a synonym for floral tube (q.v.).

theca (plur. thecae)   of an anther, one of the lobes that contain the pollen.

thorn   a short pointed woody structure derived from a reduced branch.

throat   of a tubular corolla or perianth, the region immediately within the top of the tube (Fig. 2j).

thyrse   an inflorescence type with an indeterminate main axis and determinate lateral branches (the latter often in the form of small dichasia) (Pl. 31b).

tiller   in grasses and sedges, a new leafy shoot, usually from the base of a tufted plant, or from a rhizome or stolon.

tomentose   covered with dense, soft, usually matted hairs.

toothed   of a margin that is reasonably regularly and sharply lobed (the ‘teeth’ usually small), or an apex etc. that bears a number of (usually small) pointed lobes. A rather imprecise term.

torus   the receptacle of a flower; sometimes a synonym for floral tube (q.v.).

trabeculate   of a surface, with a number of longitudinal ribs or ridges connected by numerous smaller transverse ridges.

transitional glumes   in some bamboos, referring to empty lower bracts on a spikelet axis below the fertile lemmas. These bracts may vary in number, and grade in appearance to resemble fertile lemmas. The term serves to avoid the need to find a doubtfully distinct pair of ‘genuine’ glumes at the spikelet base.

translucent   almost transparent, allowing some penetration of light.

transverse section   effectively a ‘thin slice’ taken through the short axis of a structure or organ (e.g. a leaf or ovary) and then viewed from ‘side on’, as a way of examining its internal makeup. See Figure 21. Often abbreviated to T.S.

triad   in general, a group of three. In inflorescences of conventional flowers, a three-flowered inflorescence or branch of dichasial form.

tribe   in classification, a group between the ranks of genus and family. It is generally employed when a family is large (such as the Daisies or Grasses) and greater clarity is derived from aligning the genera into tribal groups.

trichome   a general term for an epidermal outgrowth without vascular tissue such as a hair or type of scale etc.

trifoliate   with three leaves.

trifoliolate   a compound leaf of three leaflets, e.g. a clover leaf, (Fig. 14f; Pl. 16).

trigonous   triangular in cross-section, and with rounded or blunt angles. Cf. triquetrous.

trilocular   of an ovary, having three cavities (loculi) in which the ovules are contained (Fig.4e).

trimerous   in general, arranged in threes. Of a flower, when the floral parts are arranged three per whorl as in many Monocotyledons.

tripinnate   of leaves which are three times pinnately divided.

triploid   see polyploid.

triquetrous   of a structure that is triangular in cross-section and with acute angles. Cf. trigonous.

trivial name   the second word in the two-part scientific name of an organism; the specific epithet.

truncate   with an abruptly blunt end, as in a leaf apex (Fig. 17).

trunk   an upright, usually substantial, main stem. Usually referring to trees.

tuber   a swollen underground stem, or part thereof, containing stored food, and forming a seasonal organ ensuring survival of the plant.

tubercle   in general, a small rounded protuberance. In the sedge genus Eleocharis, sometimes used to refer to the persistent style-base on the nut. Some Grasses bear tubercle-based hairs, each appearing as an elongated hair arising from a small, domed or ring-like base. Adj. tuberculate, covered with small wart-like projections.

tufted   of plant habit, growing in a compact clump with the stems mostly upright.

tunic   an outer covering, often loose, thin, brownish and scale-like, on corms or bulbs. Often seen in Iridaceae and Amaryllidaceae. Adj. tunicate.

turbinate   top-shaped.

turgid   swollen.

tussock   of plant habit, growing in a tufted clump, usually perennial, often dense and rather robust. Often seen in grasses and sedges and similar species.

type /type species /type genus   when a new plant species is formally named, one of the requirements for publication is the designation of a particular specimen to be lodged in a recognised herbarium as the ‘type’ for that new name. Whatever future taxonomic decisions are made concerning this specimen or species (such as a transfer to a different genus), the ‘new’name remains fixed to the type specimen and shares its fate according to the rules and recommendations set out in the International Code of Nomenclature for Algae, Fungi and Plants. The type of a genus is one of the included species. The type of a family is one of its genera. These are issues relating only to the application of names; a type specimen, type species or type genus, may not be be morphologically ‘typical’ of its species, genus or family respectively.

umbel   an inflorescence in which the flower stalks arise at more or less the one point on a common peduncle (Fig. 10f). Adj. umbellate.

umbelloid   an inflorescence that resembles an umbel.

uncinate   hooked; with a hook at the apex.

understorey   a general term for the plants growing under the canopy of taller ones.

undulate   usually of a leaf, with a wavy margin, usually the waves in a plane at right angles to the leaf surface (Fig. 17).

unifacial   literally ‘with one surface’, e.g. of a leaf folded completely in half along the midline so that the adaxial ‘surface’ is reduced to just an edge, or terete so the adaxial ‘surface’ is reduced to a more or less definite line or groove. Cf. bifacial.

unifoliolate   describes a compound leaf that is reduced to one leaflet.

unilateral   one-sided.

unilocular   of an ovary, having one loculus (the cavity which contains one or more ovules), e.g. the ovary in the families Poaceae (Grasses), Cyperaceae (Sedges), Proteaceae (Protea Family), Leguminosae (Legume Family).

unisexual   of a flower, having reproductive parts of only one sex. Of an inflorescence or plant, having flowers of one sex.

urceolate   urn-shaped, i.e. like a rounded vase swollen in the middle with a flanged lip.

utricle   generally referring to a rather thin-walled, flask-shaped or bladdery structure loosely enclosing its contents. In the family Amaranthaceae, a fruit type derived from united carpels with a one-locular superior ovary in which the pericarp is thin and loose around the seed. In Carex (Sedge) and related genera, a flask-shaped structure that encloses the fruit. (The term is derived from Latin, and translated as a leather bag.)

valvate   usually of petals or sepals, having margins adjacent but not overlapping.

valve   of a mature capsular fruit, one of the ‘flaps’ that separate, providing the opening through which seeds are released.

variegated   usually of leaves or stems, striped or blotched with various colours, often a combination of green and pale yellow.

variety   in classification, a rank between subspecies and form. Usually reserved for plants that differ in relatively minor features from others in the same species, and which are not necessarily geographically isolated.

vascular bundle   an elongated strand of tissue specialised for the conduction of water and nutrients throughout the plant.

vegetative   of plants, those parts not directly associated with reproductive function, e.g. roots, stems, leaves.

vegetative culm   of some Carex spp. (and likely more widely applicable in Cyperaceae), the elongated stem, with nodes and internodes, of a vegetative shoot. Cf. pseudoculm.

vein   a vascular bundle with associated supporting tissue as seen in leaves or bracts, etc. A strand of conducting tissue. In plants, synonymous with nerve.

velutinous   of surface texture, velvety due to a covering of short dense hairs.

venation   the arrangement of, or pattern made by, veins. Usually referring to leaves, and then often described as either parallel or reticulate.

ventral   pertaining to or situated at the front. Of a lateral organ, the surface facing the axil, the adaxial side. Cf. dorsal.

vernation   of leaves in bud, the pattern of folding. In grasses, young leaf blades are usually either rolled or folded before they are fully developed and expanded.

verrucose   of a surface, warty. Dim. verruculose.

versatile   of an anther, when its point of attachment to the filament is small, allowing easy movement.

verticil   a whorl of three or more similar parts arising from the same node. Adj. verticillate, arranged in whorls (commonly referring to leaves).

vestigial   of a structure or part that appears to be a remnant, i.e. diminished in size and/or function from a typical condition.

vestiture   a general term for any surface covering, e.g. hairs, scales, etc.

villous   of a surface, with a covering of long weak hairs.

viscid   generally of a surface, sticky, glutinous. Sometimes used to describe the spikelets, or leaf or culm margins of certain sedges when manifesting a brownish exudate.

vitta (plur. vittae)   a longitudinal tube or canal containing aromatic oil, often seen e.g. in the fruits of Apiaceae (Fig. 132).

vivipary   the germination of seed before it is shed from the parent plant. Adj. viviparous. Sometimes used more loosely for proliferous structures (q.v.).

voucher/voucher specimen   a reference specimen, usually stored in a herbarium, retained and preserved from plant material used for some other purpose, study or research. It substantiates the identity of the research material.

weed   a term not strictly defined, but generally thought of as a plant growing where it is not wanted. Some species have characteristics facilitating weediness such as competitive vigour and high reproductive rate. Exotic species that have the capacity to invade, establish and compete successfully in indigenous ecosystems may be called environmental weeds.

web   of some grass lemmas (particularly in the genus Poa), long, fine, cottony and/or crinkled hairs arising from the basal callus region.

whorl   several similar organs arising from the same level around an axis, such as a whorl of sepals or petals (Fig. 1), or leaves.

whorled   an arrangement (e.g. of leaves) of three or more around the stem arising from one node (Fig. 15).

wing   a flap or thin extension of tissue, or expanded flattened projection, usually seen along the edge of a structure (e.g. Fig. 115c). In pea flowers, each of the two lateral petals (Figs. 66, 68c).

woody   usually seen as a general term for stems that are hard and tough as opposed to herbaceous.

xeromorphic   of a plant or species, adapted to arid habitats.

xylem   a component of the vascular tissue of plants; groups of cells involved in the conduction of (mostly) water.

zygomorphic   of flowers that are asymmetrical and can be divided into equal halves along one longitudinal plane only (Fig. 2d–f).

zygote   a fertilised egg cell.