Illinois Natural History Survey - University of Illinois

INHS Reports January-February 2000

Species Spotlight: Tulip Tree

During presettlement times, the forest along the Wabash River in Illinois contained trees of prodigious size. In 1871 Robert Ridgway, a Smithsonian naturalist, measured several of these immense trees. Among the giants were tulip trees, Liriodendron tulipifera, which were second only to the sycamores in size. Ridgway describes one of the large tulip trees: "The finest individual found prostrate was one cut for lumber near Timberville,

Wabash County, Illinois; it measured one hundred and fifty-eight feet in total length, while the trunk was twenty-three feet in circumference three feet from the base, and eighteen feet in circumference at seventy-four feet further up, where the first branch grew; the trunk perfectly sound and symmetrical throughout."

The natural range of the tulip tree lies east of the Mississippi River in the central hardwood region. The best original stands covered the rich valleys and fertile coves in association with the southern Appalachian mountain ranges and certain districts lying both east and west of them. The trees prefer deep, rich, and rather moist soil, and in Illinois, tulip trees are found in the southern two-thirds of the state.

Under forest conditions tulip trees are characteristically tall-mature trees that range from 3 to 8 feet in diameter and 90 to 100 feet in height. They lose their lower branches, rapidly resulting in straight, clear trunks. Also, they have a spreading root system with a deep, fleshy taproot and will sprout readily from a stump following a cutting or a fire. The bark on a young tulip tree is smooth and greenish gray; as the tree matures its bark becomes dark gray and is made up of straight, deep furrows with interlacing ridges. The bark is thin and easily damaged. Its twigs are reddish brown and aromatic. The winter buds are a half-inch long, dark red, and covered by two large, flattened scales, giving it the appearance of a duck bill.

Tulip trees have simple, alternate leaves of an unusual shape. These leaves are four to six inches in diameter, smooth-edged and mostly four-lobed with a broad notch at the tip. They are dark green and shiny on the upper surface and paler underneath. During autumn the leaves turn clear yellow. In May and June, after the leaves are fully expanded, the tree produces large, showy tulip-shaped flowers. These flowers are nearly two inches across and are composed of six creamy to greenish yellow petals,

Stately tulip trees and insets showing leaf (top) and flower.

often tinged with orange. The fruit is a brown upright, narrow, cone-shaped cluster of winged seeds which will ripen in September and October. Tulip trees have many different common names, depending on the region where the tree is found and its uses. Its scientific name, Liriodendron tulipifera, comes from Greek and means a tree bearing lilies. The resemblance of its flower to a tulip has conferred the name tulip tree. Wood users prefer the name whitewood, while yellow poplar is preferred by lumbermen. While called poplar, it is not correct because the species is a member of the magnolia family. One reason for the poplar misnomer is that tulip tree leaves tremble in the breeze in much the same way as true poplars.

Susan Post, Center for Economic Entomology

Charlie Warwick, editor