(Wall.) Benth.
Description
Apios carnea is widely distributed through the Himalaya and into south-east and east Asia, recorded from Nepal, north-east India, Bhutan, Myanmar, China, Thailand, Laos, Vietnam, Malaysia, Korea and Japan among its 887 georeferenced occurrences. It is a climbing herb of forest margins, thickets, streamsides and clearings in warm-temperate to subtropical settings, scrambling over shrubs and into the lower canopy. The Bhutan records at Trithangebe (1100 m, October) and Wangdi (2000 m, June) illustrate a broad altitudinal tolerance from about 1000 to 2400 m, flowering through the warm wet season.
It is a perennial twining vine arising from a tuberous, fleshy rootstock, with slender, herbaceous, somewhat woody-based stems. The leaves are pinnately compound (imparipinnate) with usually five to seven ovate-lanceolate, acuminate leaflets. The flowers are borne in dense axillary racemes and are typical papilionate legumes, flesh-pink to dull reddish or salmon, with a broad standard, incurved keel and the characteristic coiled keel-and-style of the genus. The fruit is a slender, elongate, dehiscent legume containing several seeds.
The genus Apios belongs to tribe Phaseoleae of subfamily Faboideae, allied to climbing beans, and the twisted keel enclosing the spirally coiled style and stamens is a notable floral specialisation promoting cross-pollination by bees. As a nitrogen-fixing legume it contributes to soil enrichment, and its tubers have been used locally as food. Common and widespread across its range, it is of no conservation concern, though it is regionally valued both as an ornamental climber and a wild food plant.
Author: (Wall.) Benth. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Flora of Nepal, Lackey Phaseoleae revision (Advances in Legume Systematics)