(Prain ex Raym.-Hamet) S.H.Fu
Description
Rhodiola hobsonii is an alpine succulent perennial of the eastern Himalaya and adjacent southwestern China, recorded from Bhutan, northern India (Sikkim, Arunachal), Nepal and the Chinese provinces of Xizang and Yunnan; GBIF holds about 101 records. It inhabits open stony slopes, gravelly screes, rock crevices and short alpine turf, generally between about 3800 and 5000 m, enduring intense insolation and a brief growing season. The photographed plant was collected at the Chele La pass in western Bhutan at around 4150 m in September, on the well-drained, frost-disturbed substrates it occupies near the upper limit of vascular plant growth.
The plant arises from a stout, woody, persistent caudex crowned by the scaly remains of old leaf bases, from which several short, fleshy, erect or ascending flowering stems develop. The leaves are alternate, sessile, succulent, oblong to obovate, entire or sparingly toothed toward the apex, and rather densely set. The inflorescence is a compact terminal cyme; the species is dioecious, the flowers four- or five-merous and dull purplish-red, the petals narrow. The fruit comprises several erect follicles that split to release minute seeds.
Rhodiola (Crassulaceae) is a large genus of cold alpine and arctic regions, segregated from Sedum by its perennial woody caudex and predominantly dioecious flowers. R. hobsonii belongs to the diverse Sino-Himalayan assemblage of the genus, many members of which are rich in rosavins and salidroside and used in regional traditional medicine. Restricted to high elevations, it is naturally localised but not currently assessed as threatened, though such cushion-zone specialists are vulnerable to warming.
Author: (Prain ex Raym.-Hamet) S.H.Fu · Sources: POWO (Kew), GBIF, Flora of China Vol. 8, Flora of Bhutan Vol. 1, Flora of Nepal, Flora of Pakistan, Ohba monograph of Himalayan Sedoideae and Rhodiola