Rhynchosia himalensis Seeds | Himalayan Rhynchosia
LATIN NAME: Rhynchosia himalensis
COMMON NAME: Himalayan Rhynchosia
Plant Profile
Himalayan rhynchosia is a wiry, twining herb of the middle hills, with stems that thread through scrub and over low walls rather than climbing boldly like a bean. The leaves are trifoliolate, the leaflets oval and slightly downy, and the flowers are small, yellow and pea-shaped, carried in loose axillary racemes through the warm months. They are followed by small, flat, downy pods that turn brown and split with a twist to throw the mottled seed a short distance. The whole plant is modest — rarely more than a metre of growth — and it is easily overlooked until it flowers, when the yellow clusters make it worth a second look. It grows from Pakistan through the western Himalaya to Nepal and Bhutan, on grassy banks, forest edges and terraced field margins between about 1000 and 2500 metres.
Science & Biotechnology
Rhynchosia is a large genus in the Phaseoleae, the tribe that includes beans, cowpeas and pigeon peas, and like most of that tribe it nodulates and fixes nitrogen. The genus is best known chemically for prenylated isoflavonoids — compounds such as lonchocarpin and related pyranoisoflavones — which have attracted attention for antifungal and insecticidal activity, and for the presence of rotenoids in some species. R. himalensis itself has been little studied; most of the pharmacological work in the genus concerns R. minima and R. volubilis, and it should not be assumed to transfer. The Himalayan species are of interest mainly to taxonomists working on the boundaries of the genus, which is large, variable and not yet satisfactorily resolved. The twining habit and small, explosively dehiscent pods are typical of the group.
Uses & Benefits
It is a plant for the wilder edge of a garden, or for a collector of Himalayan flora, rather than a crop. It provides quick, light cover on a sunny bank, fixes nitrogen in the root zone, and flowers over a long season with a colour that few legumes of that size offer. In its native range it is grazed by stock in the young stage and cut for fodder, and the seed is sometimes gathered in times of scarcity, though it is small and the yield is poor. There is no commercial trade in the species and no reliable medicinal use; the plants sold in the ornamental trade are grown from wild-collected seed, which is one reason germination can be uneven. It is a useful subject for a meadow strip or a pollinator margin in a warm temperate climate.
Growing from Seed
Scarify the seed lightly with sandpaper and soak it overnight, then sow it a centimetre deep in a free-draining mix at 20 to 25 °C. Germination is usually within two weeks, and the seedlings should be potted on before the taproot coils. Grow them in full sun, in poor to moderate soil, and give them a low support or a neighbouring shrub to scramble through. Plant out after the last frost. The plant is drought-tolerant once established and needs no feeding; rich soil produces leaf at the expense of flower. In a cold climate it is best treated as an annual, or lifted and kept under glass, since it is not reliably hardy below about minus five. Collect seed from the pods just as they turn brown, before they twist open.
Our Take
A modest, useful little legume for a wild corner, with nitrogen in its roots and yellow in its flowers, and no pretensions beyond that.
Related Reading
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