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
Stigmella salicis a blotch, or if highly contorted with 'S' bends, a false blotch. The larvae feed on "Myrica gale", "Salix alba", "Salix atrocinerea", "Salix aurita", "Salix babylonica", "Salix caprea", "Salix cinerea", "Salix daphnoides", "Salix fragilis", "Salix lanata", "Salix pentandra", "Salix purpurea", "Salix repens", "Salix silesiaca", "Salix triandra" and "Salix viminalis". Mines on the narrow-leaved willows can be difficult to distinguish from those of "S. obliquella". The pupa is in a yellowish-brown cocoon spun in detritus and can be found in July and August, and from November through to April. "S. salicis" is found in Europe (except Iceland and Greece). Stigmella salicis