From Workhorse to Green Man: The Oak
THE OAK FAMILY was never likely to supply a candidate for the Tree of Life. Oaks are too workaday, too down to earth, too uncompromisingly woody. They don’t aspire to symmetry or spire-like elegance, but work out their destinies through obstinate and not always pretty eccentricity. Their family name, Quercus, ought to be the root of ‘quirky’ but, perversely, seems not to be.
There are between 400 and 600 species of oak spread across the northern hemisphere, from Colombia to north-east China. The vagueness of this tally reflects not just the endless squabblings of taxonomists (by no means ended by developments in molecular biology) but also something essential about the Quercus family. It’s opportunist, mutable, full of hybrids and intensely local varieties. There are majestic white oaks in North America and small evergreen ‘ring-cups’ (so called from the wide fringes on the acorns’ cups) in South East Asia. In the New Forest there is a race of English oaks which spring into pale and short-lived leaf around Christmas and then again in the spring. The family repeatedly overthrows cultural and botanical preconceptions. Despite Britain’s belief in a special relationship with the tree, as the nation’s ‘heart of oak’, the oaks’ botanical heartland is Mexico, where there are 160 species, 109 of which grow nowhere else.
The behaviour of a single species, the Mediterranean prickly oak, Q. coccifera, typifies the family’s plastic qualities, and forty years after my first encounter I still have problems identifying the more outlandish specimens. It’s a tree mimic artist, capable of morphing into almost any imaginable arboreal form according to its circumstances. I’ve seen it as a dwarf and spiny shrub in the garrigue in Provence, grazed down to no more than four inches in height but still bearing acorns, and as a stately sixty-foot tall, ten-foot round timber tree in the Lassithi Mountains in Crete. The way a single individual can effortlessly pass between these two extremes suggests a held-in-reserve adaptability that may be epigenetic, with different forms being switched on and off according to circumstance. Q. coccifera isn’t killed by felling, fire, shade or sheep. It regrows from the stump or rootstock, and the harder it’s grazed the more protectively spiny the new leaves become. Low-intensity browsing tends to push the regenerating oaklet into the shape of a classical column, slightly ruined but determinedly upright. The shoots around the base of the shrub spread out laterally until animals are unable to reach the centre shoots – which then grow upwards, allowing the oak to ‘get away’. It may eventually become a mature tree with low branches, at which point agile browsers can scramble up and edge their way along the woody tightropes, munching foliage just as they do on the ground. It is an extraordinary sight, trees bearing animals like fruit, with sheaves of shoots, browsed bare of leaves, rising vertically from the main horizontal branches. Historical ecologist Oliver Rackham calls them ‘goat pollards’.
The family doesn’t field many record breakers. Oaks don’t figure highly in the lists of the oldest, tallest, strongest or most massive Champion Trees. But one species or other has usually been around wherever northern people have lived, and their general all-round woodiness made them pillars of regional cultures. Throughout the Neolithic era oak was a crucial raw material, providing firewood, axe handles, frames for shelters. The north European oaks Q. robur and Q. petraea can be split cleanly, even with stone axes, and flat oak planks – imaginatively provocative artefacts in a world dominated by naturally curvaceous forms – paved the earliest surviving European walkways. The Sweet Track that crosses the Somerset marshes in England is surfaced with oak planks, supported by a scaffolding of ash, lime, elm, alder and oak poles, almost certainly grown in worked coppices. The planks have mortises bored in them so that they can be pegged to the framework. The wood is so well preserved that recent advances in dating trees by their growth rings has placed the cutting of the wood precisely, at between the years 3806 and 3807 BC.
Availability and durability were northern oaks’ prime virtues. They could be turned into almost any kind of structure where long life and resistance to weathering were crucial. They supplied the timbers for Viking warships and Christian churches. In the village of Allouville-Bellefosse in northern France, a 1,000-year-old tree is known as the Chêne chapelle. Its hollow trunk hosts two fully functional chapels, built in 1669 and still used for Mass twice a year. The tree’s unlikely progression to the status of sacred architecture began when it was struck by lightning and burnt hollow. The local clergy claimed that the lightning strike was a heavenly bolt, and that the resulting hollow had a sacred purpose. During the French Revolution it became a symbol of the ancien régime and the tyranny of the Church, and a crowd attempted to burn the entire structure to the ground. But a local citizen seemed to intuit the oak’s mutable character and renamed it The Temple of Reason. It became, temporarily, a symbol of the new democratic thinking, and was spared.
The roof of Westminster Hall, which contains 600 tons of wood spanning seventy-five feet without a central support, is another ecclesiastical marvel and the most remarkable wooden roof ever made. It is one of those paradoxical (or inevitable) wooden structures where the carpenters, having dismembered large numbers of trees, then reassemble them in what is essentially a supertree, a formal arrangement of trunk and branching that would not work unless it aped the structure of its motherlode. William Bryant Logan, one of the oak’s recent biographers, explains:
Each member of a roof truss – the triangular or spire assembly of rafters – is a force made visible. Gravity flows down the roof rafters and pushes at the walls on which the roof sits. The tie beam resists, holding the two pieces in tension. Above the tie beam, the carpenter places a collar – a smaller and higher version of the tie beam – to siphon off some of gravity’s pull. Beneath the collar, a post or a pair of arched braces would let the forces cascade down to the centre of the tie beam. Beneath the tie beam, more arched braces led out to a lower level of the walls, letting the forces run out into the ground.
But in Ely Cathedral – the ‘Ship of the Fens’ – whose soaring and labyrinthine interior resembles a carved simulacrum of an oak forest, the tree’s idiosyncrasies won out over the architect’s ambitions. The inner timber tower rests on sixteen struts which are meant to be forty feet long and over a foot square, but, as Rackham remarks, ‘with all England to draw on for the timber the carpenter evidently had to make do with trees that did not quite meet this specification’. The struts taper rapidly at the top, where they had formed the crowns of their original trees; in six cases the design was altered to use trees that, even so, were not quite long enough to reach up to the spectacular octagonal lantern in the roof.
It wasn’t just the obvious strength of oak that made it a symbol of nationhood in Britain. If North Americans glimpsed their country’s pioneering spirit and unsullied, heaven-blessed landscapes in the soaring of the giant redwoods, the British saw in their sturdy, tenacious oaks, ingrained with Old World history, something of their own pugnacious and decidedly un-transcendental character. After David Garrick had published his patriotic sea shanty ‘Heart of oak are our ships/Heart of oak are our men …’, the naval historian John Charnock floated the audaciously nationalistic idea that only British soil could grow oakwood suitable for ships which aspired to the spirit of British nationhood:
It is a striking but well-known fact that the oak of other countries, though lying under precisely the same latitude as Britain, has been invariably found less serviceable than that of the latter, as though Nature herself, were it possible to indulge so romantic an idea, had forbad that the national character of a British ship should be suffered to undergo a species of degradation by being built of materials not indigenous to it …
The diversity of oak-tree form has been reflected in the ingenious and frugal uses found for its various component parts. The tannin-rich bark was used to soften hides in manufacture of leather. The leaf galls (produced by wasp larvae) were the source of an intensely dark ink, used by Leonardo da Vinci in his drawings. Acorns (balanos in Greek) crop up as phallic symbols in classical sculpture, and modern medicine has returned the compliment by naming inflammation of the penis balanitis. In Spain evergreen oaks are the mainstays of an entire rural economy. The cork oaks, Quercus suber, have their bark stripped every nine years. The acorns provide food for the local pigs. The branches, and those of neighbouring holm or live oaks, Q. ilex, are cut to increase the acorn crop, and the prunings converted to charcoal, bound for the barbecue market. The roast acorns of both species are sweet enough to be a popular Iberian bar snack for humans, sold as bellotas. The acorns of the South East Asian kunugi, a variety of Q. acutissima, are also still traded commercially as a source of starch. Modern Brits could never have granted a staple role for the intensely bitter acorns of their native oaks, but during the domestic austerities of World War II, the Ministry of Food suggested making a substitute coffee from them. They had to be chopped, roasted, ground up and roasted again. The resulting beverage was acrid and caffeine free, not a product a nation under siege was likely to take to its heart, or palate. (Another indigenous plant came to the rescue when roasted chicory roots were conscripted instead.)
Boars feeding on acorns, in the ancient practice known in Europe as ‘pannage’. This illustration is from a late medieval Latin translation of an Arab medical treatise.
The quercophilic William Bryant Logan was struck by this widespread use of acorns as human food. Researching for his book Oak: The Frame of Civilisation in 2004, he came across a map of ‘World Oak Distribution’. He was astonished to find that, in his reading, ‘the distribution of oak trees is coterminous with the locations of the settled civilisations of Asia, Europe and North America’. Japanese and Korean customs of eating kunugi acorns, for instance, were echoed on the other side of the Pacific, where indigenous North American peoples used white- and live-oak acorns as a staple source of carbohydrate. It ought to have been no great surprise. Most humans flourish in the same climatic and environmental conditions as most oak species. But Logan was sufficiently moved by the coincidence to frame a radical new theory about the origins of civilisation. He dumps the conventional idea that hunter-gatherers and early pastoralists evolved gradually into cereal farmers through close contact with the wild grasses eaten by their half-wild stock. He argues instead for an intermediate stage in which acorns – communally gathered and stored over winter – became the exclusive, worldwide prototype for centralised agriculture. Oaks and human settlements were not ‘coterminous’ by coincidence or shared habitat preferences, but because people had deliberately moved to where oaks grew, in search of the staff of life.
Few archaeologists would argue with the notion that late hunter-gatherers were collecting and storing nuts and fruit, and maybe beginning inadvertently to cultivate them, whenever discarded pips and kernels germinated near settlements. But the range of staple edibles – even of carbohydrate providers – went far beyond acorns, depending on place, habitat and season. Walnuts and apples were used in central Asia, sweet chestnuts and olives in the Mediterranean, hazelnuts in northern Europe, reed-mace pollen in parts of North America. Like all overarching theories, Logan’s Big Idea requires a lot of fanciful Eureka! moments and highly selective evidence, and its end result, ironically, is to underplay early humans’ inventiveness and the tree kingdom’s edible diversity.
The big oak at the end of our Norfolk garden is a kind of coda, a flourish of contrapuntal woodiness that says decisively: cultivation ends here. Its canopy is twenty-five yards across, a dome of craggy, arching, algaltinted ribs. Standing in its aqueous shade is like being inside some immense beached cetacean. Tawny owls, flocks of fieldfares, rising moons, the sentence I was mulling over as I wandered up to look at it, can vanish in a trice in its surf of flickering leaves. It was a long time before I could bring myself to do anything as mundane as put a tape measure round its trunk. Just over nine feet; so probably no more than a century old. That brought its stature down a peg, and for the first time in the ten years I’d lived with it I looked at it purely as a structure. I was slightly shocked to realise that my Romantic maze of wood was unambiguously geometric. Working my way round the trunk, I could see that the main side branches (the first, and biggest, grew southwards, ten feet up) were at right angles to each other, and all left the trunk at close to forty-five degrees to the vertical. Some way along each of these slanting ribs, secondary branches sprung out horizontally, at forty-five degrees below the supporting branch. And so it went on to the outermost twigs, an alternation of upward and downward forty-five degree divisions. Even the ribs in the leaves were set at this angle to the central spine. On one branch system I counted nine almost identically angled forks between trunk and leaf tip. Of all the oaks in all of Norfolk I seemed to have the one designed by Pythagoras.
If I’d had more of a surveyor’s skills and temperament – and been able to see through the tangles of ivy and bramble – I would doubtless have discovered other intimations of order in what I’d always assumed to be an epitome of anarchic growth. I might have found that the numbers of main branches followed the Golden Ratio, with five in the lowest layer, three in the next, two at the top. This is a proportion found throughout nature, in the spiral form of tornadoes and the efflorescent growth of crystals just as much as in the organic world. It has little to do with Darwinian evolution, but seems to be an inherent property of self-organised systems. There are more patterns consequent upon the laws of physics and mechanics. Leonardo da Vinci outlined one such in a formula which he believed described the organisation of all trees: ‘all the branches of a tree at every stage of its height when put together are equal in thickness to the thickness of the trunk’, a pattern which ensures that there is always sufficient branch capacity to carry the sap from the trunk. At the end of the nineteenth century, the biologist Wilhelm Roux added some riders to this formula: if a central trunk or stem forks into two branches of equal width, they both make the same angle with the original stem, and side branches small enough to make no appreciable deflection in the straightness of the main stem, diverge at angles between seventy and ninety degrees. In the 1920s, the physiologist Cecil Murray attempted to explain this by suggesting that the rules governing blood flow also applied to sap. He was studying animal arterial systems at the time, and saw analogies between these and the vascular structure of trees’ water channels. The energy required to drive blood to the point reached by an arterial side branch is minimised if narrow branches diverge at wide angles and wide ones diverge at equal or wide angles. Since trees carried water and sap in a similar fashion, why shouldn’t the principle of minimum effort apply here too? It seemed a logical explanation, and probably holds for some parts of some trees. But argument by analogy, as so often, proved to be off kilter. In 2011 the French physicist Christophe Eloy began to suspect there was an alternative explanation. By using computer models of trees of different structures and submitting them to virtual gales, he was able to prove that trees followed Leonardo’s formula – accurate enough in itself – not so much to ensure efficient transport of sap as to give their frames stability in the wind. Tree forms follow ‘the axiom of uniform stress’. The stresses they experience have to be distributed evenly over their whole structure, otherwise there are weak spots. The lean of a trunk is balanced by the counterweight of branch opposite, for instance, which is supported by thick, muscular tension wood at the joints.
As for the way the branching pattern is repeated, with the fork of trunk into branch echoed in the splaying of the twigs, the ribbing of the leaf, even in the radiation of water vessels, it is the phenomenon known as fractalism. Structural patterns echoed at an ever diminishing scale are widespread in nature, from river deltas to snowflakes, and appear again to be self-organising according to mathematical and mechanical laws. In plants they’re additionally encouraged by the economies of biology. The amount of DNA required to program plant growth so that it is based around a single structure repeated at different scales, is less than that needed to make many dissimilar structures.
Yet in the real world these are only ever ideal models, approximations to a pattern. Living plants are subject to unquantifiable and unpredictable stresses. They’re bent in the wind, raddled by fungus, shaded by their neighbours. Every Platonic pure intention is overthrown by the realities of life, which is not to achieve perfect form but to survive. Underlying patterns must help with this otherwise they would have failed the trials of evolution, but they have done so by being flexible guidelines, not rigid moulds. And we seem to prefer it that way. A tree with exactly geometric branching patterns, its branches as fractally precise as snowflakes and with every leaf identical, would not strike us as a living thing. Being ‘frayed and nibbled’, Annie Dillard writes in Pilgrim at Tinker Creek (1974), is the price of existence. It is one of the qualities that can make us become emotionally attached to old trees. They wear the arboreal equivalent of lines on the face. And some of those lines are added by us.
There are three notable oaks in my home county of Norfolk which show how the interplay between natural growth and human image making shapes real trees, which in turn shape trees of the imagination What’s known as Kett’s Oak stands by the side of the road between Wymondham and Norwich. It’s reputed to be the tree under which, in 1549, the farmer William Kett gathered his army of aggrieved local landworkers before they marched on, and briefly occupied, the city of Norwich in protest against the enclosure of common land. The original oak would have been about 600 years old by now, a giant barrel of a tree with a girth of more than thirty feet. What stands by the B1172 today is a more shrivelled thing, surrounded by a fence (but a low fence, unlike the Fortingall yew) and barely a quarter of that girth. The upper part of the trunk leans sharply away from the vertical, and is propped up by a wooden brace. The stumpy main trunk (there is just eight feet of it below the slant) is partially split and held together with metal bands. I very much doubt that it is the original tree, though it may be a regrowth from the stump after the original trunk collapsed – or was deliberately destroyed (it was a very political oak). I rather prefer this regeneration scenario. Leaning slightly away from the rushing traffic of the modern world, far from magisterial, slightly the worse for wear and affectionately looked after by the local authority, the oak is an apt and powerful symbol of the commonplace rebellion it commemorates. (There was another oak associated with Kett on Mousehold Heath, north-east of Norwich, where his 15,000 strong army was encamped. The Oak of Reformation no longer exists, but legend is that it supported a vast tent in which Kett and his helpers planned their action, like Alexander the Great on a major campaign.)
The Poringland Oak is one of the most celebrated paintings by the Norfolk artist John Crome, a member of the Norwich School, whose members prefigured Constable in their reaction against classicism and their desire to paint naturalistic landscapes and ordinary working people. The picture, made in 1818, is dominated by a young, straight and lightly branched oak. It rises beside a pond in which four village youngsters are bathing, or maybe just paddling. They are half clothed and facing away from the viewer, adding to their sense of rural informality. Whether the tree still exists is uncertain. There is an oak beside a pond in Poringland (an expanding village south of Norwich), which may well be Crome’s tree grown on for a couple of centuries, and is championed by some locals as a candidate. The land around the pond has been developed, and the tree rises in the garden of a modern, bungalowsized Free Church with attached café, faint echoes of Crome’s populism. When I look at it I’m struck by how different it is from Kett’s. It is still as straight trunked as the oak in Crome’s picture, and elegant enough to pass for a beech at a distance. Its form is worthy of a landscape garden or arboretum; the perfect model of a tree. Regardless of their authenticity and origins, Kett’s and Crome’s oaks represent two cultural types: the workaday oak of the commons, and the oak of the pastoral idyll.
The third emblematic Norfolk oak is on the ceiling of Norwich Cathedral cloisters. It is growing from the face, fine featured and long haired, of a Green Man. To be strictly accurate it is not an oak tree, but four oak leaves. But they have the look of individual trees. They’re borne on stems as proportionately thick as trunks, and their edges are crimped and finished with gold leaf, as if the whole tree is already touched with the ambivalent splendour of the Fall. This is the oak of mythic creativity.
There are eight more examples of foliate heads in the cloisters, but not all bear oak leaves. One with the face of a gigolo is shrouded in a mask of gilded hawthorn leaves. Another is cheekily diabolic, with unidentifiable leaf forms emerging alongside a tongue from a leering, beetle-browed visage in what is perhaps the most familiar format of the Green Man. The foliate head is a diverse and persistent emblem, whose meaning, or meanings, have been argued about for more than 1,000 years. Basically it consists of a human head, wreathed in or shaded by or occasionally composed of leaves, or with leaves growing out of – or perhaps into – its ears, nostrils and mouth. The different perspectives of those two prepositional possibilities show the latitude of interpretation to which the Green Man image is open. It may be a symbol of the devil, of death and new life, of the unity of humankind and nature, or just an enduring motif for a long series of cartoons.
The oldest versions date from the cusp between pre- and recorded history. Representations of the Celtic god Cernunnos show his hair formed from leaves. Sixth-century heads on Byzantine capitals sprout acanthus leaves. The first representation at a Christian site appears to be on the tomb of St Abre (now preserved at Poitiers), which dates from the fourth or fifth century. The latest Green Men – all very oaky – are purchasable as plaster facsimiles for interior decor, where they contribute to a Merrie England atmosphere alongside the real-ale bottles and cricket photos. But classic Green Men are most densely concentrated in north European churches from the tenth to the seventeenth centuries, and undoubtedly have a theological status, if not a single meaning.
Interpretations of the Green Man tend to be either stern or celebratory. Kathleen Basford, in her classic The Green Man (1978), takes the admonitory side and views foliate heads as predominantly warnings about the temptations of the physical world. She traces this strain in their symbolism to the influential eighth-century theologian Rabanus Maurus, to whom ‘leaves represented the sins of the flesh or lustful and wicked men doomed to damnation’. They stood for corrupt words issuing from the mouth, and licentious images entering the eye. By contrast William Anderson’s scholarly and pantheist Green Man (1990) is inclusive and accepting. He sees the figure as a universal symbol (the subtitle of his book is An Archetype of our Oneness with the Earth). He tracks apparent changes in the style of the heads through time and through the physical structures of the Church. The earliest seem the most satanic. The faces are relentlessly fierce. They have open mouths, bared teeth, protruding tongues. During the Renaissance the heads become softer, and begin to develop the believable features of real people. The vegetation surrounds the face more often than protruding from its orifices. They can be found in all kinds of situations inside churches. Anderson suggests that, when positioned by the choir, their leaves represent the issuing of the Word, in song or litany. Over doors through which the living enter and the dead exit they may be memento mori, reminders that ‘all flesh is as grass’.
Yet formulaic interpretations don’t fit with the exuberant variety of form and ingenious placing of foliate heads. They can be found high up amongst gargoyles and hidden under choir benches. They show the huge influence of the individual carver’s imagination and personal sense of humour, or reverence. There are Green Men which are caricatures of village elders, terrifying portents of damnation, clever visual puns. One of the most beautiful in England, a fourteenth-century carving in Sutton Benger church in Wiltshire, features a face with an expression of patient resignation, and emerging from its mouth are sprays of hawthorn in which two thrushes are busy eating berries. In the church in Brome, Suffolk, ancient but renovated in the Victorian period, the mason has carved one distinguished but rather bland foliate face, and next to it an ingenious cluster of oak leaves, in which the gaps between the lobes appear like the eye holes in a carnival mask.
I’ve seen many Green Men across Europe and think that over the centuries they developed into an all-purpose design feature, a logo endowed with the perennial magnetism of the chimera, and an irresistible eye-worm for stone carvers. Many were doubtless intended to have religious or spiritual significance, but more, I suspect, were created for mischief or ornament, or because they seemed the most apt image to make at a particular spot in a church. A few appear to be used as a kind of vase, in which to root the stone foliage that wreaths about the walls.
The thirteenth-century ‘Green Man of Bamberg’ in Bamberg Cathedral, a foliate face unlike any other.
The Lady Chapel of Ely Cathedral, forty miles west of Norwich, has one of the most elaborate leafy interiors in England. Many of the images of Mary on the columns were smashed or decapitated during the Reformation, but the Green Men and the symbolically sinful foliage were puzzlingly left intact. There is tremendous cluster of truly diabolical, leering faces (including, uniquely, a foliate fox mask) on its vaulted ceiling, and a head on one of the columns which is more village fool than dirty devil. His lolling tongue turns into a stalk which winds across the chapel wall, morphing into leaves, lobes, fruit, tendrils. It is as if the carvers’ imaginations worked analogously to the growth of vegetation – ‘taking a vine for a walk’, to misquote Paul Klee’s definition of drawing. A sombre plaque announces that ‘this is a place of brokenness reminding us of the brokenness of our world’. On the contrary, the exuberant carving seems a celebration of the unbroken connectivity of the living world. Outside the chapel there are exact leaf and flower carvings everywhere, not just oak, but maple, strawberry, buttercup, hawthorn – all eventually leading to the lines of floral decoration that rise up on the oak fan vaulting of the octagonal lantern.
That there were obvious comparisons to be made between Gothic architecture and the disposition of wood and foliage in trees fascinated the nineteenth-century writer on art and architecture John Ruskin. His views on leaves were ambivalent. He was repelled by the idea of photosynthesis, which invited us to regard leaves as, in his word, ‘gasometers’ – a view which on the surface seems on a par with his disgust at the notion that the structure of flowers was for the benefit of insects rather than aesthetically minded humans. The arbiter of Victorian taste saw beauty in nature as a benediction from God on those with the eyes to see. Yet the remarkable passages on the development of foliage in Part V (‘Leaf Beauty’) of Modern Painters are devoted to understanding the needs of the growing and leafing plant itself. He notes how the leaves in the cluster – the ‘star’ – at the end of an oak twig are never equal or symmetrical. ‘Nature cannot endure two sides of a leaf to be alike. By encouraging one side more than the other, either by giving it more air or light, or perhaps in a chief degree by the mere fact of the moisture necessarily accumulating on the lower edge when it rains, and the other always drying first, she contrives it so.’ Later, in a section called ‘The Law of Resilience’ he continues:
The ubiquity and versatility of foliate form.
Oak-leaf carved from snow for a contest whose motif was ‘feathers’.
[T]he leaves, as we shall see immediately, are the feeders of the plant. Their own orderly habits of succession must not interfere with their main business of finding food. Where the sun and air are, the leaf must go, whether it be out of order or not. So, therefore, in any group, the first consideration with the young leaves is much like that of young bees, how to keep out of each other’s way, that every one may at once leave its neighbours as much free-air pasture as possible, and obtain a relative freedom for itself … But every branch has others to meet or cross, sharing with them in various advantage, what shade, or sun, or rain is to be had. Hence every single leaf cluster presents the general aspect of a little family, entirely at unity among themselves, but obliged to get their living by various shifts, concessions, and infringements of the family rules.
Heartened by this burst of arborocentrism in Ruskin, I went back to the oak in my garden and tried to re-envisage it as a compromise between geometric order and the realities of neighbourhood life. Even at a century old it’s wearing the badges of experience. I can see that the first big southward branch has grown to balance out the lopping of others on the northward side, where the tree overlooks a worked field. The next branch up lopes eastwards for fifty feet, rippling like a shallow wavelet as it rises and falls over the remains of a hedge, until it is clear of the mother tree’s canopy, where it shoots vertically upwards with the clear ambition of becoming a second trunk. Not a single branch is following a straight line. They’ve been deflected by past ice falls, beetle invasions, and by what seems like a gratuitous and universal urge to wander about. Here and there I can see more abrupt turns and kinks, and through binoculars I can make out fracture marks and scar tissue where branches have been snapped by the wind and had to renew growth in a different direction. I try to follow a single limb, imagining it as a three-dimensional graph, logging the branch’s adjustments to over-shading and manoeuvres into spaces of light and still air. For a few feet it becomes a whirlpool of wood, an ‘infringement of family rules’. It bends to ride over the branch beneath, which in its turn is trying to evade the presence of this intrusive sun shade. At the point where the two come closest together there are radical attempts at a breakout, with U-bends, actual shedding of branch ends and sheaves of compensatory twigs. All this is happening in no more than a cubic yard – a cameo of the whole oak family’s protean nature.