(D.Don) A.Dietr.
Description
Henckelia bifolia is a Himalayan gesneriad recorded from India, Nepal, Bhutan and Sri Lanka, with about 124 georeferenced occurrences indicating a distribution along the humid southern Himalayan and northeast Indian foothills. It is a plant of warm, shaded, moist habitats: it grows on dripping rock faces, shaded banks, ravines and the floor and margins of subtropical broadleaved forest, generally at lower montane elevations, broadly from about 800 to 1800 m. The illustrated material was gathered at Zhemgang in Bhutan at 1000 m in October, a low, humid forested setting typical of the species, which flowers toward the close of the monsoon season.
It is a small perennial herb, often nearly stemless, with the leaves few and basal; as the epithet bifolia implies, the plant frequently develops a pair of opposite, sometimes markedly unequal leaves that are ovate, soft-textured, crenate to toothed and pubescent. The flowers are borne on slender axillary peduncles in few-flowered cymes; the corolla is zygomorphic, tubular and bilabiate, pale violet to bluish-lilac, with a short erect upper lip and a larger spreading three-lobed lower lip. Two stamens are fertile, and the superior ovary matures into the straight, narrowly cylindrical capsule diagnostic of Henckelia.
Henckelia (Gesneriaceae) was recircumscribed in the molecular reclassification of the didymocarpoid gesneriads, absorbing many species previously placed in Didymocarpus and Chirita; the name listed here as the family, Didymocarpinae, is in fact the subtribe to which Henckelia belongs, and the species properly sits in Gesneriaceae. The genus is characterised by its straight undivided capsules and bilabiate flowers. As a humid-forest understorey herb of restricted, fragmented habitats, H. bifolia depends on intact low-montane forest, and although not formally assessed it is potentially vulnerable to deforestation.
Author: (D.Don) A.Dietr. · Sources: POWO (Kew), GBIF, Flora of Bhutan, A Revised Handbook to the Flora of Ceylon, Weber & Möller revision of Henckelia (Gesneriaceae)