Wall. ex. D.Don.
Description
Thunbergia coccinea Wall. ex D.Don is a vigorous woody climber of the eastern Himalaya and Indo-Burmese region, with GBIF documenting nearly 692 occurrences across India, China, Nepal, Bhutan, Myanmar, Thailand, Laos, Sri Lanka and Bangladesh, alongside numerous cultivated records in tropical and subtropical gardens worldwide. In the wild it scrambles through the canopy of moist broadleaved and subtropical forest, along streamsides and forest margins, flowering in the post-monsoon months. The illustrated plant from Wangdi (Wangdue Phodrang) in western Bhutan at 2500 m in September captures it at the upper edge of its altitudinal range, twining over shrubs and trees in humid hill forest.
The species is a perennial liana with twining stems and opposite, petiolate leaves that are ovate to cordate, acuminate, with toothed to entire margins and palmate basal venation. The flowers hang in long, pendulous, many-flowered racemes; each scarlet to brick-red corolla is tubular and curved with a slightly oblique, shortly five-lobed limb, subtended by paired bracteoles, and contains four didynamous stamens. The fruit is the characteristic acanthaceous capsule, beaked and explosively dehiscent, ejecting a few flattened seeds borne on retinacula.
Thunbergia, sometimes segregated in Thunbergiaceae but generally placed in Acanthaceae, comprises Old World tropical climbers and shrubs, several grown ornamentally; T. coccinea is valued in horticulture for its dramatic drooping red flower chains. Its bird- and insect-visited blooms point to a mixed pollination syndrome. The species is widespread and not of conservation concern, though as a forest liana it depends on the persistence of intact moist montane and submontane woodland.
Author: Wall. ex. D.Don. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Acanthaceae of the Indian Subcontinent, Bremekamp studies on Thunbergia