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 babylonica northern Syria in 1730. These plants are all females, readily propagated vegetatively, and capable of hybridizing with various other kinds of willows, but not breeding true from seed. This type of tree is grown very easily through plant propagation. Two cultivated hybrids between pendulous "Salix babylonica" and other species of "Salix" willows also have pendulous branchlets, and are more commonly planted than "S. babylonica" itself: Cultivars derived from either of these hybrids are generally better adapted than "S. babylonica" to the more humid climates of most heavily populated regions of Europe and North America. A similar willow species also native