Thanks to Bian Tan, I now know that it is Desmodium umbellatum. Its Malay names include 'Petai laut'. According to Burkill, in Singapore and the Moluccas, the young leaves were eaten as a vegetable. Which may account for another Malay name for the plant: 'Lemak ketam'.Corners describes it as a straggling shrub or small tree to about 3m, "often prostrate towards the sea". Indeed, those plants I saw at Pulau Hantu did just that, the branches leaning way out to form a low umbrella over the sandy shore, while their trunks were at the highest water mark. 'Umbella' means parasol or umbrella, possibly referring to this growth form?
The leaves are made up of three leaflets that are oval or have a blunt tip, thinly leathery and hairy beneath. According to Selvam, the middle leaflet is always larger (6-8cm long) than the side leaflets.
The flowers are small (1-1.5cm) creamy white in short clusters.
The brown pod is short (3-4cm) curved with 3-5 segments and 1-4 rather thick joints. The small seeds are hard and oval. According to Selvam, pods that break into one seed units are sticky and thus spread by animals and human. It is reported that seeds are also dispersed by the sea. The plant also has a pretty pattern on its bark.According to Corners, it is found along the coasts and tidal rivers and common in Malaya on sandy, muddy and rocky ground. According to Hsuan Keng, it was found along the coasts all around Singapore island and on Pulau Senang. According to Selvam, it can forms dense stands along the coast. It also grows as an under story in low-elevation forests.
According to Selvam, it is a nitrogen fixing plant and excellent in controlling soil erosion. In the Maldives, straight sticks are used as beams along the length of the roof and also as sides of the traditional timber built houses. Straight branches are also used as handle for scoops used for drawing water from wells. Charcoal produced from the wood is widely used by blacksmiths. Leaves are used as in a tonic for women after childbirth. It is also grown as an ornamental plant.
There were two of these bushes on Pulau Hantu. The plant is not listed among our threatened plants, but I don't recall seeing them. I guess I just haven't been observant.
Bian points out the shape of the flower, which is typical of the pea family of legumes (this plant is listed under Family Fabaceae). He also points out that the constricted pods that break off joint by joint are also characteristic of the genus Desmodium.
Thanks for the id Bian! And sharing tips on how to id this plant.
Bian is conducting a workshop on our Pioneer Plants with the Leafmonkey Workshop on 8 May. So come for the workshop if you'd like to learn more about our plants from Bian!
References
- Hsuan Keng, S.C. Chin and H. T. W. Tan. 1990, The Concise Flora of Singapore: Gymnosperms and Dicotyledons. Singapore University Press. 222 pp.
- Corners, E. J. H., 1997. Wayside Trees of Malaya: in two volumes. Fourth edition, Malayan Nature Society, Kuala Lumpur. Volume 1: 1-476 pp, plates 1-38; volume 2: 477-861 pp., plates 139-236.
- Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
- Burkill, I. H., 1993. A Dictionary of the Economic Products of the Malay Peninsula. 3rd printing. Publication Unit, Ministry of Agriculture, Malaysia, Kuala Lumpur. Volume 1: 1-1240; volume 2: 1241-2444.
- V. Selvam. 2007. Trees and Shrubs of the Maldives. on the FAO website
