Rootstock a horizontally spreading, perennial rhizome. Stem twining to left. Bulblets present or absent. Leaves alternate, usually simple, rarely 3-foliolate; leaf blade glabrous or shortly stiffly hairy, margin entire to deeply palmately lobed. Male inflorescence a spike, raceme, or thyrse, sometimes branched, sometimes gathered into a terminal panicle by reduction of subtending leaves. Flowers usually in cymules of 2--4, solitary distally on inflorescence, sessile or pedicellate; bracts borne at base of pedicels; perianth lobes connate at base; stamens 6, sometimes 3 reduced to staminodes. Capsule reflexed at maturity, about as long as wide, rarely longer than wide. Seeds inserted near middle of capsule and winged all round, rarely inserted near base with wing pointing toward capsule apex.

Several species are of medicinal importance.

About 35 species: temperate Asia, extending into Malaysia and W to the Caucasus and Balkans, a few species in North America; 18 species (eight endemic) in China.