As I ride home from work each day, I usually find my eyes drawn to a yard of White Poplar trees that have trunks as white as a sheet of paper and leaves that glimmer as they quiver in the breeze. I stopped one day to inspect them more closely, and found an even more interesting feature: dark diamond-shaped marks appearing in the white bark in a regular pattern. I saw many small suckers coming up around the trees and considered taking one home- until I noticed matted roots spread over the surface of the yard. Erring on the side of caution, I left the suckers alone and decided to admire these beautiful trees from a distance.
The White Poplar trees I admired are also known as Silver-leafed Poplar. These trees are in the willow (salicaceae) family, with the scientific name Populus alba. In Greek mythology the White Poplar was consecrated to Hercules after he destroyed Cacus next to a hill of White Poplars. He bound his brows with a White Poplar branch as a token of his victory. Due to this tale, it became customary for victors in battle to wear garlands of White Poplar. The Poplar most probably got its name from its use in Ancient Rome to decorate public (or popular) places. It was known as arbor populi, or tree of the people.
The White Poplar is native to Central and Southern Europe, and Central Asia. It was introduced to North America in 1748, when it was brought to a nursery in Philadelphia. This unusual and easily propagated ornamental spread to almost every state, and quickly became looked down upon much as a weed for its invasive nature.
The leaf of the White Poplar is quite interesting as it quivers in the breeze. The top of the leaf is dark green and smooth, contrasting with its tomentose (wooly) white or silver underside. Young leaves are 1.5” to 2.4” and palmate (shaped like an open palm) with wavy edges and a flat base. Late season leaves are typically twice that size, with 3 to 5 palmate lobes and wavy edges. Leaves are alternate, hanging by tomentose (hairy) twigs on tomentose branches.
White Poplar trees have a single upright trunk with spreading branches, but they often appear in clusters of two or more. The trunks and branches are white with a smooth texture. Diamond-shaped lenticels or pores begin to appear in a regular pattern on trunks that have reached a diameter of 6 inches. As the tree continues to age, the lower trunk becomes rough and darkens to dark gray or black. The cross section of a twig reveals a star shaped center pith with 5 points. The tree may grow 80 feet in height and over 3 feet in diameter, but it is not known for long life.
Propagation of White Poplar trees is primarily through root suckers from the tree’s shallow and extensive root system. Root suckers can occur at any time but appear very aggressively when the parent tree or any roots are cut or damaged. Large numbers of suckers from a single tree can quickly develop into a dense colony. The tree produces female and male flowers on separate trees in March or April. Female flowers are catkins that are yellow-green, and male flowers are catkins that are red. Since only female trees were planted when this species was introduced to North America, you should only find yellow-green catkins. This means the tree does not reproduce sexually except by hybridizing with other poplar species. Fertilized female catkins develop into tiny seeds possessing a tuft of silky white hairs that are easily spread by the wind in late summer.
White Poplar is a beautiful ornamental that would be an excellent specimen to have in an open area park that is well managed. However, this is not a tree to use in a yard landscape. This soft hard wood is weak making it prone to wind and storm damage. The extensive shallow root system can be a problem with driveways, foundations, and septic tanks. The aggressive suckering nature of this tree makes it hard to do anything about problem roots or removing a tree. There is a reason we see so few of these trees in the Atlanta area- even though they can be easily grown here. This is one tree that is best admired from a distance.