Herbs perennial. Principal roots robust, woody. Stems pulvinate or caespitose. Leaves sessile, subulate to linear, always persistent, margin narrowly membranous, apex aristate. Flowers solitary or paired, rarely more in terminal inflorescences. Sepals lanceolate to ovate-lanceolate, 3-veined, midvein raised, lateral veins not obvious, margin white membranous, apex acute. Petals white, rarely pink, shorter than or equaling sepals, rarely longer than them. Floral disc scalloped lobed, glands 5, conspicuous.

About 20 species: Asia and North America; 17 species (12 endemic) in China.