(Wall. ex G.Don) S.Schauer
Description
Sorbus ursina is a Himalayan rowan distributed along the southern margins of the high mountains, with documented occurrences in Nepal, India, China, Myanmar and Bhutan, and a comparatively modest record base of around 126 georeferenced collections. It is a tree of the upper temperate to subalpine forest belt, typically occupying the transition between mixed broadleaved-coniferous woodland and the open shrub zone, where it grows on cool, humid, often steep slopes and along forest margins. The plant photographed at Seema in Garhwal (India) at about 3450 m in June reflects this characteristic elevational preference, where the species ascends to the upper limit of arborescent vegetation amid Abies, Quercus and ericaceous undergrowth.
It forms a small deciduous tree or large shrub with a spreading crown, the young twigs initially tomentose and becoming glabrescent and dark with age. The leaves are imparipinnate (pinnately compound), comprising numerous oblong to lanceolate leaflets that are sharply serrate along the margins, glabrous and green above and conspicuously paler, frequently whitish-tomentose, beneath. The flowers are borne in many-flowered terminal corymbs and are small, pentamerous and white, with five free petals, numerous stamens and a partly inferior ovary. The fruit is a small subglobose pome, ripening through pink to deep red and often persisting on the branches after leaf-fall.
Within the large and taxonomically intricate genus Sorbus, S. ursina belongs to the pinnate-leaved (subgenus Sorbus) assemblage, a group complicated across the Himalaya by hybridisation and apomixis. The conspicuous autumn fruiting renders it ecologically important as a food source for thrushes, accentors and other montane frugivorous birds, which act as the principal seed dispersers. Although not presently regarded as threatened given its broad range, populations are tied to intact subalpine forest and are therefore sensitive to grazing pressure, fuelwood collection and the upward shift of timberlines.
Author: (Wall. ex G.Don) S.Schauer · Sources: POWO (Kew), GBIF, Flora of China Vol. 9, Flora of Bhutan Vol. 2, Flora of Nepal, McAllister The Genus Sorbus: Mountain Ash and Other Rowans