(Raym.-Hamet) H. Ohba
Description
Rhodiola cretinii is a high-alpine succulent perennial of the Himalaya and adjacent Tibetan region, recorded from China, Nepal, India and Bhutan, with around 140 occurrences in GBIF. It is a plant of the upper alpine zone, growing on rocky slopes, screes, cliff ledges, moraines and stony turf, typically well above the treeline between about 3800 and 5000 m. The photographed material was collected in Bhutan at Jule-Tso at 4100 m in June, an elevation and rocky alpine setting fully consistent with the genus's affinity for cold, exposed, free-draining high-mountain ground.
The plant arises from a stout, fleshy, often woody caudex or rootstock crowned with the persistent remains of old leaf-bases. The flowering stems are short and erect, densely clothed with small, fleshy, alternate, sessile leaves that are flat to terete and entire or finely toothed at the apex. The flowers are crowded into a compact terminal cyme; like many alpine Rhodiola the species tends to be dioecious or functionally unisexual, the small flowers with greenish-yellow to reddish, often four- to five-merous perianths. The fruit is a cluster of erect to spreading follicles, each splitting to release numerous minute seeds.
Rhodiola, segregated from Sedum, comprises crassulacean stonecrops specialised for cold, arid and high-elevation habitats, employing succulence and a perennating caudex to survive harsh alpine winters. Several Himalayan species are harvested for traditional medicine, and although R. cretinii is not prominently exploited, slow-growing alpine perennials of this kind are inherently vulnerable to over-collection and habitat disturbance. Its compact cushion-like growth and dense leafy stems are typical adaptations to wind exposure, intense radiation and a short growing season.
Author: (Raym.-Hamet) H. Ohba · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Rhodiola monograph (Ohba)