Herbs perennial, usually with stout rhizome. Stem erect, simple, basally with a few brown, scalelike sheaths. Leaves 3, in a terminal whorl, sessile or shortly petiolate, rhombic-orbicular to ovate, with 3 or 5 main veins and anastomosing veinlets. Flowers bisexual, solitary, terminal, pedunculate. Tepals 6, in 2 whorls, free; outer ones usually green, persistent; inner ones petaloid, rose purple to white, slightly narrower than outer, withering or deciduous after anthesis. Stamens 6; filaments short; anthers basifixed, linear, with very short connective. Ovary ovoid to globose, 3-loculed; ovules several to many per locule. Style short, deeply 3-lobed often to base. Fruit a berry, globose to ovoid. Seeds several to many, ovoid, small.

About 46 species: Bhutan, China, India, Japan, Korea, Myanmar, Nepal, Russia, Sikkim; North America; four species (one endemic) in China.

(Authors: Liang Songyun (梁松筠 Liang Song-jun); Victor G. Soukup)