Deciduous trees with fissured bark. Leaves alternate, simple, biserrate, penninerved with oblique bases; stipule scarious, variable in size, caducous. Flowers appear before leaves on previous years branches in clusters, usually bisexual. Perianth campanulate, 4-8 lobed ,imbricate. Stamens as many as perianth segments. Ovary compressed; style short, deeply 2-fid, papillose on the inner side to the base. Fruit a flat samara surrounded by a broad membranous wing.