型態特徵

Dioecious scandent or erect shrubs to trees with sympodial branching. Bud scales single fused into a cap or with free overlapping margins. Leaves deciduous, simple, alternate, margin glandular-serrulate to entire, petiolate or sessile, stipulate. Aments ascending to spreading, developing before (precocious), with (coetaneous), or rarely, after (serotinous) the leaves, solitary, sessile, or terminating a short, leafy branchlet. Bract with an entire apex. Nectary usually a single, short, adaxial protuberance, or partly surrounding the stipule in female flowers, sometimes with a second abaxial gland or several lateral glands connte as a ring. Stamens 2-, 3-7(-8); filaments free, sometimes connate below. Pistils bicarpellate, unilocular, stipitate or sessile, style 1, stigmas 2, entire or bifid, placentae parietal, ovules 2-12 per carpel. Capsules bivalvate, valves recurved. Seeds green, surrounded by an arillate coma.