Shrubs low, usually less than 50(-100) cm tall. Catkins usually terminal or sometimes lateral, cylindric, with leaflets at base. Male flower: stamens 2, distinct; adaxial and abaxial glands present (abaxial rarely absent). Female flower: adaxial gland only present, rarely a small abaxial gland; ovary pilose or glabrous, sessile or subsessile (except in a few species).