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 cinerea Salix cinerea Salix cinerea (grey willow; also occasionally large gray willow or grey sallow) is a species of willow native to Europe and western Asia. The plant provides a great deal of nectar for pollinators. It was rated in the top 10, with a ranking of second place, for most nectar production (nectar per unit cover per year) in a UK plants survey conducted by the AgriLand project which is supported by the UK Insect Pollinators Initiative. It is a deciduous shrub or small tree growing to high. The leaves are spirally arranged, 2–9 cm long and 1–3 cm broad