Herbs , taprooted annuals or rhizomatous perennials, rightward-twining. Stems usually branched, armed with rigid 2-branched, stalked hairs that facilitate climbing. Leaves simple; petioles often twining, with 2-branched hairs. Leaf blade mostly cordate, palmately lobed, sometimes unlobed; surfaces abaxially resin-dotted and×or gland-dotted. Inflorescences: staminate inflorescences axillary and terminal, cymose panicles, erect to pendent, (10-)20-100+-flowered, flowers small; pistillate axillary, spikes or racemes, flowers solitary or paired, short-pedicellate, subtended by bracts and bracteoles. Staminate and pistillate flowers usually on different plants. Achenes lenticular or terete, ensheathed by brownish or sometimes mottled persistent perianth; embryo coiled. x = 10.
