CATALPA

Catalpa speciosa, C. bignonioides (and Paulownia tomentosa)

                       

IMPORTANCE: Tenacious trees widely admired in cities for their jumbo heart-shaped leaves, showy late-spring blossoms, and long, dangling seed capsules. Fast growth and pollution tolerance are urban pluses; messy litter a minus.

FAMILY: Bignoniaceae (Trumpet creeper). GENUS: Catalpa (catalpa).

COMMON URBAN SPECIES: Northern catalpa (Catalpa speciosa) or western c., hardy c., cawtawba tree, cigar tree, Indian bean tree. Southern catalpa (C. bignonioides) or common c., catalfa, catawba, smoke bean tree, Indian bean tree, caterpillar tree, fish-bait tree.

CLOSE RELATIVES: Paulownia (Paulownia tomentosa) or foxglove tree, empress tree, princess tree.

TYPICAL CITY LOCATION: Residential streets, parks, cemeteries, rail routes, undeveloped areas with moist soil.

KEY FEATURES: Northern catalpa: Grows tall, with medium-stout trunk and large angular limbs, a Halloweenish look in winter.

Big, down-pointing heart- or spade-shaped leaves, tropical look; 7–12″ long, fuzzy undersides, largest on young trees.

Flowers appear late in spring. Trumpet-shaped blossoms form pyramidal clusters up to 1′ tall. Each blossom roughly 2″ wide, ruffled, white with yellow and purple speckles inside.

Dangling fruit capsules are 10–24″ long “string beans,” green, ripening to brown in fall. Inside are many thin flat seeds with “beards” at each end.

Southern catalpa: Leaves are smaller, emit strong odor when crushed. Tree achieves less height, to 60′ or so. Blossoms more profuse, more purple-spotted. Seed “beards” are pointed; northern c.’s are rounded.

AVERAGE MATURE SIZE IN CITY: 40–70′ high, 1½–3½′ thick.

RECENT CHAMPION: Northern: 107′ height, 85′ spread, 20′ circumf., Lansing, Mich. Southern: 69′ height, 71′ spread, 18′ circumf., Palestine, Tex.

RICH BOUQUET, BAD CIGAR

For all its beauty, the catalpa finds itself rebuffed by the more fastidious landscapers. They consider it a high-maintenance slob, throwing off copious litter during three seasons. Yet, with its big heart-shaped leaves and towers of ruffled blossoms, it wins aficionados in almost every town where it can grow.

“String bean” capsules up to two feet long dangle from catalpas in fall.

Dangling brown seed pods give it the nickname “cigar tree,” but a good cigar is decidedly not one of the catalpa’s virtues. Up to two feet long, the pods looks more like giant string beans than Havanas. Those who have puffed a pod are sorry for it.

The pods (actually capsules) do make for wonderful sights. In summer they dangle like exotic jade pendants. In winter they fringe the branches. But even without them, the catalpa would stand proudly in urban settings. It is a fast-growing, husky tree, thick enough to support heavy limbs. In less than 10 years it can shade a house. Mature trees commonly reach 50 feet and now and then surpass 100. A 107-footer rises on the Michigan State Capitol grounds.

The catalpa is a lush tree, displaying cascades of big green valentine-heart leaves, wide end up. Given space, the tree can spread its canopy outward and cast cellar-dark shade as broad as its height. It is the catalpa’s floral display, however, that brings a tropical touch to northern cities and a late rush of beauty after magnolia, apple, and other early blossoms have disappeared.

Around June, the flowers rise in vertical, conelike clusters called panicles, sometimes towering 10 to 12 inches above the twig (as large as horse-chestnut panicles, though not so prettily mounted on candelabra-like branches). Making up each panicle are trumpet-shaped blossoms up to 2½ inches wide at their ruffled, scalloped mouths. Within the white petals, lavender and gold speckles and trails attract pollinators. A ripe (some say cloying) aroma also draws the nectar crowd. Individual blossoms resemble small orchids. The full flowering tree becomes a gown of velvety green festooned with white corsages.

ROYAL LOOK-ALIKE: THE PAULOWNIA OR PRINCESS TREE

There is no “cigar” on this catalpa look-alike, but the fragrant deep purple flowers of the royal Paulownia (Paulownia tomentosa) have won it a place in eastern America, where it appears in gardens and as an escapee to roadsides. A fountain at Philadelphia’s Logan Square is ringed by these beauties.

Introduced from China and named after a Dutch princess, the tree also goes by the common names princess, empress, cotton, karri, and foxglove tree. One of the most vigorous deciduous trees, it grows rapidly and as high as 40 to 50 feet. Botanists differ on its family classification—some place it with the figwort family, others with the trumpet creepers as a cousin of the catalpas. The flowers are similar in shape (not color) to the catalpa’s, but the leaves are slightly more angular and the seed capsules entirely different. Rather than long, dangling string beans, the capsules look like clusters of small castanets. Each capsule contains some 2,000 winged seeds ready to take flight to a roadside near you.

NORTH VS. SOUTH

Most of the catalpas seen in North America are of two species: northern catalpa and southern catalpa, each with a host of other popular names (see summary data). They overlap broadly in their growing regions and to casual viewers look and act more or less the same. The southern catalpa, however, is likely to have a smaller, thicker leaf with a shorter point and considerably more blossoms on each panicle, with more lavender or purple coloring. The northern catalpa can grow considerably taller than the southern, although neither species gets much beyond 40 to 60 feet high in cities.

To distinguish the trees, a scratch-and-sniff test is conclusive. Crush a leaf (ideally, a freshly fallen leaf) and smell it. If it emits a strong, unlovely odor, the tree is a southern catalpa or part southern. Another determinant: Open one of the fallen pods in autumn and examine its papery seeds, which are bearded at the tips. On southern catalpas, these silvery beards come to a point. On northerns, they are blunt or rounded, like Abe Lincoln’s.

Which is the more impressive tree, northern or southern? That depends on one’s tastes. For massiveness, northern has the edge. For flowers, southern is more seductive—discounting the unsavory leaf. For adaptability, although northern has survived -30°C winters in Montreal, southern may still win out: Not only can it crossbreed with certain other species, but it has flourished far beyond its south-central U.S. origins. First cultivated in 1726, it is planted from Seattle to New York, as well as in southern Europe. An observer with the Brooklyn (N.Y.) Botanic Gardens reports that 95 percent of the catalpas she finds appear to be southerns.

Big, heart-shaped leaves set off the catalpa’s showy summer blossoms.

‘Aurea’, a golden-leafed cultivar of the southern catalpa, has been called “the nearest thing to a permanently sunlit hill” (Hugh Johnson). A cross with a Chinese catalpa has created the ‘Purpurea’, whose burgundy spring leaves are often seen around town before they fade to green in summer.

Northern or southern, it makes no difference to one particular catalpa lover as long as the tree is there for dinner. The caterpillar larva of the catalpa sphinx moth feeds on catalpa and only catalpa, often defoliating the branches in its frenzy. The tree may not be happy to see these black and yellow pests, but many a fishing enthusiast prizes “catalpa worms” as bait. In some communities, the catalpas may be raised primarily to host the bait, though not every tree is infested. Most catalpas can survive a defoliation or two, but a succession of attacks can be fatal. Nor does the infested tree benefit from stick beatings, reportedly administered to shake the worms loose.

ROMANCE OF THE GENUS

Catalpa species, native also to China and the West Indies, have enjoyed some high moments in civilization. As one of four primary trees of the Chinese gods, catalpas were planted in strategic temple sites to please divinities. Today, the yellow flowers and long, thin fruit of a Chinese species sometimes enjoy the honor of being eaten.

The name “catalpa”—pure music when drawled in the American South—came to English from the Creek tribal language, where it meant “head” plus “wing,” possibly in relation to the flower. (Some sources credit the Cherokees for the name.) Native Americans derived a poultice from the leaves and a purgative from leaves and bark, neither extract making medical history.

A one-man campaign put the tree on the U.S. map in modern times. Around 1900, an Indiana engineer became a near-fanatical proponent of northern (“hardy”) catalpa power. Secretary of the International Society of Arboriculture, he boosted the easy-to-grow tree at the 1904 Louisiana Purchase Exposition in St. Louis, promoting what he believed were its rotproof qualities and industrial uses. Soon a number of railroads were creating catalpa plantations along their rights-of-way, hoping to use the timber for ties, telegraph poles, and fence posts. Farmers planted catalpas as windbreaks and commercial orchards.

Then troubles came: poor soil, mixing of species, catalpa worms, fungus, root rot, and a rot that could destroy even the resistant heartwood if it found its way in. The commercial projects failed, but an army of plantation workers had enjoyed a stretch of employment, and the tree had established itself around the country.

With some pruning and maintenance, the catalpa will deliver on its promise as a dramatic, shade-giving, sturdy ornamental for urban landscapes. Some city forestry departments, such as Chicago’s, continue to recommend it as a durable street tree where space allows. And one respected Website—of This Old House—named it as one of “Twenty-one Trees for the Next Millennium.”

You’ll be seeing it around for a while.