Willow (Salix spp.) includes a large group of deciduous trees and shrubs commonly found along rivers, lakes, and wetlands throughout the temperate regions of the Northern Hemisphere. Hardy to zone 2, willows grow rapidly and are well adapted to moist soils and flood-prone landscapes. Many species develop slender, flexible branches and narrow leaves that move easily in the wind, giving the trees a graceful, flowing appearance. Mature trees can range from medium-sized shrubs to tall spreading trees depending on the species. In early spring, willows produce soft catkins that provide one of the first important food sources for bees and other pollinators. Their extensive root systems help stabilize riverbanks and prevent erosion. Medicinally, the inner bark of several species has been used for centuries as a natural pain reliever and fever remedy due to its salicin content. Because of this property, willow is often considered one of the historical plant sources that inspired the development of modern aspirin.