Chamaerhodiola Nakai; Clementsia Rose.

Herbs perennial, with some dimorphism. Rhizome a fleshy caudex, thick or slender, apex usually at or slightly above ground level. Caudex leaves present, usually reduced and scalelike, but sometimes with well-developed leaf blade. Flowering stems 1 to many, arising from axils of caudex leaves, annual, simple, leafy; dried remains of old stems sometimes persisting. Stem leaves usually alternate, occasionally verticillate or opposite, simple, fleshy. Inflorescences terminal, a simply or compoundly corymbiform or dichotomous cyme, less often 1-flowered, rarely a helicoid cyme or with additional axillary inflorescences arising from distal leaf axils, usually bracteate and pedunculate. Flowers usually bisexual, sometimes unisexual (when plants dioecious, or gynodioecious in Rhodiola alsia subsp. alsia and rarely in R. purpureoviridis subsp. phariensis). Calyx (3 or)4- or 5(or 6)-parted. Petals ± free, as many as sepals. Stamens in 2 series, usually 2 × as many as petals; antepetalous stamens adnate to basal part of petals; anthers mostly purple before anthesis, later turning yellow, basifixed or less often dorsifixed, 2-loculed. Nectar scales linear, oblong, suborbicular, or quadrangular. Ovary superior; carpels as many as petals. Follicles few to many seeded.

Sedum carnegiei Raymond-Hamet (Ann. Carnegie Mus. 8: 418-420. 1913), known only from Xizang (near Lhasa Shi), seems to be a possible member of Rhodiola, based on the turnip-shaped caudex, stem leaves with a basal spur, specialized flowering stem/lateral inflorescence, and deeply divided calyx and corolla. It differs from other members of that genus in its caudex leaves, which are fleshy and lack the persistent, scalelike base characteristic of other members of Rhodiola. The habit is like that of Rosularia. The exact generic placement needs further investigation.

Rhodiola multibracteata H. Chuang (Acta Bot. Yunnan. 19: 225. 1997) has been described from Yunnan. No material has been seen by the present authors, and it has not been possible to place it within the following key. In the protologue, it was compared with R. kirilowii, from which it was said to differ in having narrower leaves, many bracts, hardly unguiculate male flower petals, and erect follicle beaks. Its relationship to that species needs investigation.

About 90 species: high altitudes and frigid zone of N hemisphere; 55 species (16 endemic) in China.