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Vigna marina (Burm.) Merr. 1917
pronounced: VIG-nuh mar-EE-nuh
(Fabaceae – the pea family )
subfamily: Faboideae – the bean subfamily
common names: Sea Bean, Notched Cowpea
Vigna is named for Dominico Vigna, an Italian botanist who lived in the first half of the 17th century. He was Professor of Botany and Director of the botanical garden at Pisa, and wrote a commentary on the works of Theophrastus; marina is from the Latin marinus, of the seaside.
This is a little foreshore plant, photographed growing among the beach morning glory (Ipomoea pes-capræ ssp. brasiliensis) and other dune vegetation just above the high tide mark at Geoffrey Bay. In Australia it occurs in the Northern Territory, Cape York Peninsula, and down the east coast as far as central NSW; it is also found in Asia, Malesia and the Pacific Islands. It grows on frontal dunes and beach ridges.
Vigna marina is a slender vine with stems 2–3 m long and often purplish striped. The light green leaves are trifoliate, on stalks 2–5 cm long, arranged alternately along the stem. Each leaf consists of 3 triple-nerved leaflets that are broadly ovate to oblong, 4–10 cm long and 2–5 cm wide. The leaflets have smooth edges and rounded tips. Stipules are present at the point where each leaf stalk joins the stem; they are ovate to lanceolate, peltate or medifixed.
The fruit consists of a rounded pod up to 8 cm long and 6 mm thick. The drooping pods twist after opening to release the seeds. Each pod contains 4 – 9 circular to oblong greyish brown seeds.
As a legume, it is equipped to fix nitrogen from the air surrounding its roots. Micro-organisms present in nodules on the roots convert nitrogen from the air into a form that plants can use. The process improves the nitrogen content of the sand and helps the growth of other dune plants. Vigna will tolerate a certain amount of salt spray and sandblast, but usually does not survive complete burial under windblown sand. It often forms dense stands when growing in combination with sand spinifex grass, and is a useful species for planting in protected situations on the crest and landward side of frontal dunes and beach ridges, to aid in stabilizing foreshores.
The plant can be propagated from seed, which is usually readily available from established stands. A light mechanical scarification, or heat treatment, will break seed dormancy and assist germination. Nursery-raised seedlings can be planted out in spring to early summer. Direct sowing of the seed into moist sand in sheltered parts of the dune or ridge will also sometimes give good results.
In Hawaii, the leaves, stalk, midrib, and stems were pounded until soft and applied to wounds, boils and ulcers. The roots of the plant were roasted and eaten by some of the indigenous peoples of northern Australia.
Larvae of the moth Trigonodes cephise feed on the plant.
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
Photographs taken at Geoffrey Bay 2011
Page last updated 8th March 2017