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 myrtilloides new leaves appear. The leaves resemble bilberry ("Vaccinium uliginosum") leaves in shape, hence the name in the Finnish and Swedish languages, which translates as "bog bilberry willow". A very similar, closely related species, "Salix pedicellaris" (bog willow), occurs in northern North America; it is classified as a variety of swamp willow "S. myrtilloides" var. "pedicellaris" by some botanists. Salix myrtilloides Salix myrtilloides, the swamp willow, is a willow native to boglands in cool temperate to subarctic regions of northeastern Europe and northern Asia from central Norway and Poland eastwards to the Pacific Ocean coasts, with isolated populations further south in