Tree of the Month, June 2024

by Martin (Mort) Schmidt

Tuliptree, Tulip Poplar, Tulip, Yellow Poplar, Whitewood, Canoe Tree

for Simply Living

Mature Tuliptree. Photo by Mort Schmidt.

Tuliptree is one of our commercially most important trees. At the lumberyard, it’s often called “Yellow Poplar” or simply “Poplar”, but it’s not a poplar, it’s a magnolia. Tulip is classified as a hardwood because it has leaves, but in fact the wood is softer than some conifers – the so-called “softwoods”. Nevertheless, Tulip is a useful and attractive tree, enough so that it’s the State Tree of several states, and a commonly-planted tree in Europe. 

Liriodendron tulipifera has simple, alternately-arranged leaves, meaning that each leaf has its own stem and is attached directly to the permanent parts of the tree. Compound leaves have multiple leaflets on a stem in more-or-less constant numbers, for example, the three leaflets associated with Poison Ivy. Alternately-arranged leaves and branches are not directly across from each other, but are staggered left, right, left, right. 

Left to right – alternately-arranged, oppositely-arranged, pinnately-veined, palmately-veined. Images by Mort Schmidt.

L. tulipifera leaves are very distinctive, starting in winter when they’re just buds. Many tree buds, including Ohio Buckeye (Aesculus glabra), are covered by obvious scales, but Tuliptree has two parts (valves) that resemble a duck’s bill. The bud opens up to reveal a leaf with four or six lobes. At first glance, the leaf might be mistaken for Sugar Maple (Acer saccharum). But most maples have an odd number of lobes, with one point at the end of the leaf, whereas Tulip leaves have two tips with a depression between them. Also notice that the Tulip leaf is pinnately-veined, with a single primary vein and secondary veins attached at different points. Sugar Maple is palmately-veined, with several primary veins radiating from the base, like the fingers in the palm of your hand. Also notice in the figures below, that the length of lobes on Tulip leaves is highly variable, and that there are sometimes more than four points, but they’re always even in number. 

Clockwise from upper left – Tuliptree buds, three Tuliptree leaves with variable degrees of lobing, and Sugar Maple leaf. Compare the Tulip’s pinnate veins with the maple’s palmate veins in the lower left. Photos by Mort Schmidt.

Tuliptree (L. tulipifera, Tulip Poplar) gets its name from its greenish-yellow tulip-like flower. Flowering plants are classified primarily on the basis of flowers and fruits, and secondarily on the basis of leaf shape. Tuliptree is in the magnolia family, in which tulip-like flowers are the norm. The only other member of genus Liriodendron is L. chinense, which is native to China and Vietnam. The Asian species is planted in landscaping in Europe and the U.S., but differs in having more deeply-lobed leaves and lacking yellow color in its flowers. (I usually assume that in forests, I’m looking at the native Liriodendron, but in town, it’s not obvious which is which without flowers). Each flower is said to contain up to a teaspoon of nectar, but the flower has little fragrance, at least to humans. The flowers contain hard spines, many of which persist into winter, making the tree recognizable most of the year. The spines contain a seed at one end, and fall off to start anew in spring. 

Tuliptree flowers and seeds. Photos by Mort Schmidt.

Liriodendron tulipifera bark is quite distinctive on the juvenile tree, and, to my eye, resembles lizard skin. As the tree matures, it often continues to have lighter-colored bark between ridges. Mature bark has a sort of diamond pattern, similar to Black Walnut, Bitternut Hickory, and White Ash, but the diamonds are broken up with small, repetitive peck marks – it takes getting used to, and it’s still not always obvious. The best bet for winter identification is to look for the flowers and the duck-bill buds.  

Left – juvenile Tuliptree bark. Center and right – mature Tulip bark. Photos by Mort Schmidt.

Tuliptree is the tallest eastern hardwood and can attain great stature relatively quickly. Ohio’s Champion Tuliptree, located in Preble County, has a height of 176 feet, a trunk diameter of 4.8 feet (182 inches CBH (circumference at breast height)), and a crown width of 114 feet. Donald Culross Peattie’sA Natural History of Trees of Eastern and Central North America states that Tuliptrees as tall as 200 feet once grew in the Appalachians. Even now, the Monumental Trees website reports a North Carolina specimen with a height of 192 feet. 

Tulip Poplars in winter. The persistent flower structures often make Tuliptree recognizable from a distance in winter. Photos by Mort Schmidt.

ID Summary: Summer – leaves with two tips, and briefly, green and yellow tulip-like flowers. Winter – hard flowers that break into spines, and buds resembling duck bills. 

Tuliptree is native to eastern North America. It grows best in moist, well drained soil, often on hillsides. It also does well in urban environments, but its potentially large size limits placement. Lucy Braun’s The Woody Plants of Ohio indicates that Tulip is found in most of Ohio, but is absent in a handful of western counties and several northeastern ones. Tuliptrees were widespread in prehistoric times, but were reintroduced to Europe in recent centuries. Unlike Black Cherry and Northern Red Oak, Tulip Poplar is not invasive there, and is a favorite tree for landscaping large spaces. 

Liriodendron tulipifera range map. Image from U.S. Geological Survey.

Tulip poplar is one of the largest and fastest-growing hardwoods of the eastern U.S., making it a highly valuable resource. Tulip lumber has a Janka hardness of 540 lbf and a density of 0.40 g/cc, according to the Wood Database, compared to the median of my list of 73 Ohio trees of 1,075 lbf and 0.64 g/cc. Tuliptree’s hardness is lower than that of some conifers, including Eastern Red Cedar (Juniperus virginiana). But Red Cedar is classified as a softwood and Tuliptree as a hardwood because the former is a conifer and the latter is not. Although L. tulipifera (“poplar” at the lumberyard) is relatively soft and has low rot resistance, it’s easy to work, it takes stain, paint, and finishes well, and is available in large sizes at low cost. Tuliptree is widely used for wood trim, veneer, plywood, and pulp. Many of Ohio’s covered bridges were built of Tulip, because it was available in large sizes without knots, and its limited strength was offset by its low weight. Poplar’s low rot resistance is a drawback, but that’s why covered bridges were covered. Until the 1900s, paint had little protective value and was mostly used to decorate. Bridges were covered with wood to protect the beams, and the covering was simply replaced periodically. And because Poplar was cheap and abundant, both the bridge coverings and shingles were often made of Poplar. 

Tulip Poplar is the State Tree of Indiana, Kentucky, and Tennessee. 

Laura C. Martin’s The Folklore of Trees and Shrubs reports that the American settlers used bark extracts to treat fractured limbs, cuts, bruises, and snake bites. A poultice made of leaves was said to alleviate headaches. Green bark was chewed as a stimulant and aphrodisiac. Like the Indians, the settlers hollowed out Tuliptree logs to make canoes, leading to another name, “Canoewood”. Rebecca Rupp’s Red Oaks & Black Birches, The Science And Lore Of Trees says that Daniel Boone built a 60-foot poplar dugout to move his family down the Ohio River to Missouri. (The Lewis and Clark explorers similarly made dugout canoes of Cottonwood, as discussed in the August 2021 Tree of the Month).  

Noel Kingsbury’s Hidden Histories: Trees, The Secret Properties of 150 Species, indicates that Tuliptree flowers produce copious supplies of nectar, but its strong taste makes it unpalatable to some unless it’s diluted with nectar from other plants. Kingsbury also states that Yellow Poplar resists termites. 

Diana Wells’ Lives of the Trees, An Uncommon History, relates a claim by the 18th-century Swedish traveler, Peter Kalm, that an infusion of Tulip bark had been known to cure malaria. (But he also reported that an old woman cured malaria by placing a spider web inside of a baked apple and eating it). Kalm also made a more credible claim regarding Tuliptree, that cattle enjoyed eating its leaves and it gave the milk a pleasant flavor. 

Tuliptree is widely used for reforestation because of its preference for sunlight and its rapid growth. But because of its tendency for rapid vertical growth, it keeps its crown above neighboring trees and becomes part of mature forests. 

According to the Native American Ethnobotany Database, the Cherokee made extensive use of L. tulipifera bark infusions to treat pinworms, cholera infantum, dysentery, rheumatism, coughs, fever, and snakebite. They used the wood to make canoes, furniture, and paper. The Rappahannock people used leaves to make an analgesic, and they chewed green bark as a stimulant and an aphrodisiac. 

Deer browse on Liriodendron tulipifera leaves in summer and twigs in winter. The flowers are pollinated by beetles, flies, bees, and hummingbirds. The seeds are eaten by birds, including cardinals, goldfinches, chickadees, and finches. Small rodents also eat the seeds. 

Image by Mort Schmidt.

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