Willow are very cross-compatible, and numerous hybrids occur, both naturally and in cultivation. A well-known ornamental example is the weeping willow ("Salix × sepulcralis"), which is a hybrid of Peking willow ("Salix babylonica") from China and white willow ("Salix alba") from Europe. The hybrid cultivar 'Boydii' has gained the Royal Horticultural Society's Award of Garden Merit. Numerous cultivars of "Salix" L. have been developed and named over the centuries. New selections of cultivars with superior technical and ornamental characteristics have been chosen deliberately and applied to various purposes. Most recently, "Salix" has become an important source for bioenergy production and for
Salix fragilis frequently with the type. It is a smaller shrubby tree, rarely exceeding tall, with completely hairless leaves up to 9 cm long and 2–3 cm broad. According to some botanists, it is a distinct species (treated as "Salix decipiens" Hoffm.), with, in this view, "S. fragilis" then being a hybrid between "S. decipiens" and "S. alba". Some other botanists regard "S. decipiens" as itself being a hybrid between "S. fragilis" and "S. triandra". Little evidence supports either of these suggestions. It readily forms natural hybrids with white willow "S. alba" in Europe and Asia, the hybrid being named "Salix" ×