Willow Tree
genus Salix

Shrubs and trees of the genus Salix, family Salicaceae, mostly native to north temperate areas, valued for ornament, shade, erosion control, and timber. Salicin, source of salicylic acid used in pain relievers, is derived from certain willows. All species have alternate, usually narrow leaves and catkins, male and female on separate trees; the seeds have long, silky hairs. Copyright © 2000 Encyclopedia Britannica