A. Berger
Description
Sedum triactina is a succulent herb of the eastern Himalaya and Sino-Himalayan region, recorded from China, Nepal, India and Bhutan; its c. 329 georeferenced records span a wide temperate to subalpine altitudinal range. It grows on damp rocks, mossy banks, cliff ledges, stream margins and forest floor, generally between 1500 and 3500 m. The two Bhutanese localities documented in the image, Dochu-La at 3200 m in September and Trashigang at 1570 m in May, illustrate the species' broad ecological tolerance, occurring both in cool subalpine forest passes and warmer mid-elevation valleys.
It is a small, fleshy perennial herb with slender, often decumbent to ascending stems rising from a delicate creeping base, sometimes rooting at the nodes. The leaves are succulent, alternate, oblong to spathulate, entire and rather flat, glabrous and somewhat glaucous. The inflorescence is a lax, few-flowered terminal cyme. The flowers are typically pentamerous (the epithet "triactina" alluding to a three-rayed or three-parted character in some flowers), with narrow, spreading, pale yellow to greenish-yellow or whitish petals, ten stamens, and free or basally connate carpels. The fruit comprises several spreading, many-seeded follicles releasing minute seeds.
Described by A. Berger, S. triactina belongs to the large genus Sedum of the stonecrop family Crassulaceae, a group employing CAM photosynthesis as an adaptation to the desiccating conditions of rock and cliff microhabitats. Its small flowers are visited by generalist insects, and vegetative fragmentation supplements seed reproduction. The species is widespread and locally common across its montane range, with no recognised conservation concern, persisting readily on disturbed rocky and roadside substrates.
Author: A. Berger · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Flora of Nepal, 't Hart & Bleij's account of Sedum (Crassulaceae)