Nutt.
Description
Rhododendron leptocarpum is an Eastern Himalayan endemic restricted to the moist temperate and subalpine belt of Sikkim, Bhutan, adjacent India, southern Tibet (China) and northern Myanmar, where GBIF documents some 119 georeferenced collections across the four countries CN, IN, MM and BT. It is an epiphytic or terrestrial shrub of mossy fir and Rhododendron forest, frequently perching on trunks, boulders and humus-laden ledges in a cool, perhumid, fog-bathed climate. The photographed plant at Lachung in northern Sikkim, growing near 3600 m and flowering in May, is typical of its altitudinal range of roughly 2700-4000 m.
The species is a small, twiggy shrub, often pendulous or scandent when epiphytic, with thin, flaky bark and slender, scaly young shoots. The leaves are evergreen, coriaceous, elliptic to oblong-lanceolate, glossy above and densely lepidote beneath, the scales golden to ferruginous. The campanulate to broadly funnelform corolla is comparatively small, pale to deep yellow, sometimes flushed greenish, borne in few-flowered terminal umbels; the stamens are 10 and the slender style is sharply deflexed. The diagnostic fruit is an elongate, narrowly cylindrical, curved capsule, the slenderness of which gives the epithet leptocarpum ('slender-fruited').
Placed in Rhododendron subgenus Rhododendron, the lepidote (scaly-leaved) rhododendrons, R. leptocarpum belongs to a group of small-flowered yellow species centred on the wettest Eastern Himalayan ranges. Its epiphytic habit and narrow elevational and geographic span make it a sensitive indicator of intact, high-humidity cloud forest, a habitat increasingly fragmented by grazing, fuelwood collection and warming-driven upslope shifts of the forest belt.
Author: Nutt. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, The Rhododendron Handbook (Royal Horticultural Society), Cox & Cox A Encyclopedia of Rhododendron Species