D.Don A.Dietr.
Description
Henckelia pumila is a small gesneriad of the eastern and central Himalaya and adjacent Indo-Burma, recorded from China, India, Nepal, Myanmar, Bhutan, Thailand and Vietnam, with close to 600 occurrences in GBIF. It is a plant of shaded, humid habitats, growing on moist rock faces, mossy boulders, stream banks and shaded earth cuttings within evergreen broad-leaved and subtropical hill forest. Its wide altitudinal amplitude is reflected in the collection localities given for the illustrated material, ranging from the Rathong Chu in Sikkim at 1200 m in August and Galephug in Bhutan at only 600 m in October up to Simkarok in Indian Garhwal at 2680 m in September, indicating tolerance of both warm subtropical and cool temperate forest understorey.
The plant is a small perennial or facultatively annual herb with a short, often weak stem and crowded, opposite or subopposite leaves that are ovate to elliptic, crenate-serrate and softly hairy, frequently somewhat fleshy and unequal in a pair. The flowers are borne singly or in few-flowered cymes on slender peduncles from the leaf axils. The corolla is tubular and weakly two-lipped, white to pale lilac or bluish, often with a yellow throat or coloured markings, with the lower lip the more spreading. There are two fertile stamens with coherent anthers, and the ovary is superior, developing into the slender, elongate, twisted or straight loculicidal capsule typical of the genus.
The family is given as Didymocarpinae on the source page, the subtribal name within the Gesneriaceae to which Henckelia belongs; the species is correctly a member of the Gesneriaceae. The genus Henckelia has been substantially recircumscribed following molecular study, with numerous Asiatic didymocarpoid species transferred into and out of it, and H. pumila sits within this Sino-Himalayan radiation of rock-dwelling gesneriads. Its capacity to colonise moist shaded rock and its broad elevational range make it locally frequent, and it is not regarded as threatened.
Author: D.Don A.Dietr. · Sources: POWO (Kew), GBIF, Flora of China Vol. 18, Flora of Bhutan Vol. 2, Flora of Nepal, A Revision of the Genus Henckelia (Gesneriaceae)