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 triandra other willows having two or five stamens. The scientific name derives from the male flowers having three stamens. The English common name refers to the similarity in leaf shape to almond leaves. The variety "Salix triandra" var. "hoffmanniana" Bab., found in Great Britain, is distinguished by being smaller (rarely over tall) and densely branched, with smaller leaves 2–7 cm long and 1-2.5 cm wide not glaucous below. It is not considered distinct by all authorities, particularly on continental Europe, so its range outside Britain, if any, is not reported. "Salix triandra" readily forms natural hybrids with "Salix viminalis", the hybrid