Description from Flora of China
Herbs perennial, sometimes woody at base, monoecious. Rhizome robust. Stems erect, angled. Leaves exstipulate, 1–3-pinnate, rarely 3-foliolate; leaflets sharply doubly serrate. Inflorescence a large, spikelike, many-flowered panicle; peduncle and pedicels pubescent and sparsely stellate hairy; bracts and bracteoles linear-lanceolate. Flowers sessile or subsessile, unisexual, rarely bisexual. Hypanthium cupular, with ringlike disc on rim. Sepals (4 or)5(or 6), persistent in fruit, triangular, abaxially glabrous or nearly so, margin entire, apex acute. Petals 5, white, obovate, base cuneate, apex obtuse. Male flowers: stamens 15–30, borne on rim of hypanthium; filaments slender, longer than petals; carpels obsolescent. Female flowers: filaments short; anthers sterile; carpels 3 or 4(–8). Follicles glabrous, pendulous in fruit, dehiscent along adaxial suture. Seeds 2.
Three to six poorly defined species: N temperate zone; two species (one endemic) in China.
(Authors: Gu Cuizhi (Ku Tsue-chih); Crinan Alexander)