The graceful form of the weeping willow tree (Salix babylonica) originated in China. Also known as Babylon weeping willow, the tree now grows along ponds, streams and creeks or in gardens and landscapes in North America. The telltale sign of a weeping willow is the long branches that help soften the landscape while swaying in the slightest breeze.
A deciduous tree, weeping willow grows up to 70 feet in height and width. It features a short trunk with lots of golden-yellow branches with a dropping habit. The lance-shaped leaves grow up to 5 inches long with pointed tips. In the spring, inconspicuous yellow flowers appear as catkins. The male flowers appear on one tree while female flowers grow on another. After the flowers fade, small fruits appear, consisting of light brown capsules containing small seeds. In the fall, the leaves turn yellow before falling off the tree.
Willow trees reproduce in several ways, including wind and water dispersal of the small seeds thanks to long silky hairs that help them travel up to 60 miles from their source. Another way weeping willows reproduce is from stems and twigs that break off, sometimes taking root in the soil near the tree, forming new seedlings.
Weeping willows grow best in part to full sun in USDA hardiness zones 2 to 9. The trees thrive in almost any type of soil, including clay, loam, acidic, sand and alkaline, and grow in areas with flooding. When the tree grows away from a water source, it requires regular watering to prevent its leaves from prematurely dropping in drought conditions.
Native Americans used willows as medicine, chewing young twigs and bark to alleviate headaches. Later research showed that the active ingredient in the twigs and bark consisted of salicylic acid, the ingredient used in making modern aspirin. Willow trees work well as single specimens or planted as a group used as a windscreen along property line or other borders. Since the trees thrive in standing water, they help contain erosion by spreading their roots to slow the flow of water and reducing aeration. The tree provides temporary shelter and nesting habitat for birds and small mammals, but the fruits from the tree do not attract wildlife or birds.
Willow trees can form thick groves of trees that may change the course of water, causing erosion and flooding. According to the Eastern Forest Environmental Threat Assessment Center, when the leaves fall off trees growing near streams in the autumn, the decaying leaves reduce the quality of the water and available oxygen. This decline threatens aquatic plants and animals. Weeping willows should not be located near sewer or underground water lines; the roots may cause significant damage.