(Royle) Boriss.
Description
Rhodiola coccinea (Royle) Boriss. is a high-alpine succulent of the stonecrop family ranging across the mountains of Central and High Asia, recorded by GBIF in 818 occurrences from China (CN), Nepal (NP), India (IN), Pakistan (PK), Afghanistan (AF) and Bhutan (BT) westward through Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, Russia and Mongolia. It is a plant of rock crevices, screes, moraines and stony alpine turf at very high elevations. It was photographed in West Nepal at Kalmura at 4200 m in June, well within the upper alpine zone where it endures intense radiation, drought and frost.
The plant grows from a stout, branched, woody caudex crowned with persistent papery leaf-bases, from which arise numerous short, densely leafy flowering stems. The leaves are small, fleshy, sessile, linear to oblong and entire or minutely toothed, crowded along the stems. As in many Rhodiola the species tends toward dioecy, with male and female flowers usually borne on separate plants in compact terminal cymes; the small flowers have four or five sepals and petals, the latter typically dark red to purplish, giving the epithet coccinea. The fruit is a cluster of erect, several-seeded follicles.
Formerly placed in a broadly circumscribed Sedum, Rhodiola is now well established as a distinct genus characterised by the persistent caudex and frequently unisexual flowers, an adaptation to the harsh, pollinator-poor alpine environment. Several Rhodiola species, notably R. rosea, are harvested for adaptogenic compounds, and high-elevation taxa such as this are of interest as cold- and drought-tolerant models. Its remote, rocky habitat affords some protection, though localised harvesting and climate change threaten alpine cushion communities.
Author: (Royle) Boriss. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Nepal, Rhodiola monograph (Ohba; Crassulaceae of the Himalaya)