Despite their names, white poplar (Populus alba) and tulip poplar (Liriodendron tulipifera) are not related; they belong to different tree families. While white poplar is part of the Populus family, containing poplars, cottonwoods and aspens, tulip poplar hails from the Magnolia family. These two trees are suitable for landscaping in North America, serving different functions, with both growing best in full sun locations.
Also called silver poplar, the white poplar is native to southern and central Europe as far east as eastern Siberia. White poplar, introduced to North America in colonial times, grows as a naturalized species in southern Canada and across much of the United States. White poplar is cold hardy to U.S. Department of Agriculture plant hardiness zone 3 and grows into zone 8. Tulip poplar, also called yellow poplar or tulip tree, is a native species from southern New England west to eastern Illinois and southward to the Gulf Coast. It is suitable for USDA zones 4 through 9.
Even though white poplar averages between 60 and 100 feet tall, it does not compare in size to the tulip tree, which grows to 150 feet on occasion. The tulip tree is one of the largest of all eastern hardwood species, according to the "National Audubon Society Field Guide to Trees: Eastern Region." Trunk diameter in this species averages between 2 and 3 feet, with some trunks growing much wider. The largest white poplars have trunks 2 feet wide.
The foliage on a white poplar features coarse teeth, dark-green color and develops to as long as 5 inches. The leaves look like maple leaves, with between three and five lobes. They turn yellow in autumn. White poplar generates yellow flowers in spring of little ornamental vale, but the gray-white bark is smooth and adds much to the tree’s appearance. Tulip trees take their name from the tuliplike shape of the leaves. The foliage is as wide as 8 inches and it turns golden in fall. The flowers closely resemble those of tulips, combining green, yellow and orange shades into an upright bloom late in May. The bark is gray and full of furrows.
Landscapers prefer to employ white poplar away from driveways and streets because the roots tend to penetrate and cause pavement to buckle. White poplars grow rapidly, giving them worth as a windbreak species or for the creation of privacy screens. Naturalized areas are also appropriate venues for white poplar. The tulip tree needs a large and open space in which to mature. It is a good choice as a shade tree or as a lawn tree.