Alnus (genus) en

Genus containing about 30 species of ornamental shrubs and trees that are primarily north temperate in distribution, but range south through the Andes to about latitude 20 degrees S. It is only in the Americas that members of the family extend along the mountains into the Southern Hemisphere. An alder may be distinguished from a birch by its usually stalked winter buds and by cones that remain on the branches after the small, winged nutlets are released. The scaly bark is grayish brown in some species and almost white in others. The oval leaves are alternate, serrate, and often shallowly lobed; sticky on unfolding but glossy when mature, they fall without changing colour. Male and female flowers are borne in separate catkins on the same tree; they form during the summer and usually blossom the following spring before the leaves open.