3034

11: Auxiliary plants

Pongamia pinnata (L.) Pierre

Fl. For. Cochinch.: t. 385 (1899).

LEGUMINOSAE - PAPILIONOIDEAE

2n = 20, 22

Pongamia glabra Ventenat (1803), Millettia novo-guineensis Kanehira & Hatusima (1942), Derris indica (Lamk) J.J. Bennett (1971).

Pongam, Indian beech (En). Pongame oil tree (Am). Arbre de pongolote (Fr). Indonesia: bangkong (Javanese), ki pahang laut (Sundanese), kranji (Madurese). Malaysia: mempari, kacang kayu laut (Peninsular), biansu (Sarawak). Philippines: bani (general), balikbalik, balok (Tagalog). Singapore: seashore mempari. Laos: (do:k) ko:m ko:y. Thailand: khayi (Chumphon), yi-nam (peninsular). Vietnam: d[aa]y m[aas]u, d[aa]y kim, kh[oor] s[aa]m hoa.

Pongamia pinnata probably originated from India and occurs naturally or naturalized from Pakistan, India and Sri Lanka throughout South-East Asia to north-eastern Australia, Fiji and Japan. It has been introduced in Egypt and the United States (Florida, Hawaii).

Pongamia pinnata provides two sources of energy: the wood is burnt as a cooking fuel, while the seed-oil is used for illumination. The wood also provides timber for cabinet work and cartwheels and paper pulp. The oil is applied as a lubricant, as a leather dressing in the traditional Indian tanning industry, and in manufacturing soap, varnish and paint. Pongamia pinnata is used in reforestation of marginal land, its extensive root system making it valuable for checking erosion. In Sri Lanka it is grown as a wind-break. The leaves, flowers and seed-cake are used as green manure, the leaves and seed-cake also as fodder. The flowers are a good source of pollen and nectar, yielding a dark honey. The bark can be made into rope. Medicinally, extracts from the leaves, bark and seed are applied as anti-septic against skin diseases and rheumatism. Pounded and roasted seeds used to be utilised as a fish poison. In rural areas, dried leaves are stored with grain to repel insects. Pongamia pinnata is used as a host of the lac insect and of the hemi-parasitic sandalwood Santalum album L. It is occasionally planted as an ornamental because of its attractive flowers. However, the large amounts of flowers, leaves and pods that it regularly sheds make it not very suitable for this purpose.

The energy value of the wood is 19 000—20 000 kJ/kg, its specific gravity about 650 kg/m³. The yellowish-white wood is coarse, strong, hard and beautifully grained, but not durable. It has a tendency to warp and split in seasoning. Wood fibre is 1000—1200 µm long, 20 µm in diameter and its wall about 4 µm thick. Air-dried seed contains per 100 g: moisture 19 g, protein 18 g, oil 28 g and the flavonoids karanjin 1.25 g and pongamol 0.85 g. The seed-oil has a disagreeable odour, is difficult to refine and is inedible. It contains about 70% oleic acid and 11% linoleic acid. The oil and soap made from it have a characteristic reddish-brown colour due to the compound isolonchocarpin.
The seed-oil is being tested as an anti-feedant and insecticide against several insects, e.g. Oryzaephilus surinamensis and Tribolium castaneum (both storage pests of rice) and Nephotettix virescens (a vector of the virus causing tungro disease in rice). The oil and its components are being tested as synergists to increase the potency of other insecticides.

Evergreen or briefly deciduous, glabrous shrub or tree with spreading branches, 15—25 m tall, trunk up to 80 cm in diameter. Bark smooth or faintly vertically fissured, grey. Branchlets with pale stipule scars. Leaves imparipinnate, pinkish-red when young, glossy dark green above and dull green with prominent veins beneath when mature; leaflets 5—9, ovate, elliptical or oblong, 5—25 cm x 2.5—15 cm, obtuse-acuminate at apex, rounded to cuneate at base. Inflorescence raceme-like, axillary, 6—27 cm long, bearing pairs of strongly fragrant flowers; calyx campanulate, 4—5 mm long, truncate, finely pubescent; corolla white to pink, purple inside, brownish veined outside; standard rounded obovate, 1—2 cm long, with basal auricles, often with green central blotch, thinly silky hairy; wings oblong, oblique, slightly adherent to obtuse keel; stamens 10, monadelphous, vexillary one free at base, joined to the tube in the middle. Pod short-stalked, oblique-oblongoid to ellipsoid, flat, 5—8 cm x 2—3.5 cm x 1—1.5 cm, smooth, thick-leathery to subwoody, beaked, indehiscent, 1—2-seeded. Seed compressed ovoid, 1.5—2.5 cm x 1.2—2 cm x 0.8 cm, with a brittle coat.
Growth of young trees is fairly slow; a growth of 1.3 m in height and 0.4 cm in diameter in 13 months was found in India. In Florida, it sheds its leaves in April and develops new leaves and flowers from May onwards. In India, seed ripens from February to May. Pods do not open naturally and must decay before seed can germinate. Pongamia pinnata nodulates and fixes atmospheric nitrogen with Rhizobium of the cowpea group.
The taxonomy of the genus Pongamia Ventenat is confused. It is closely related to and is sometimes included in the genera Millettia Wight & Arnott or Derris Lour.

In its natural range, Pongamia pinnata tolerates a wide temperature range. Mature trees withstand light frost and tolerate temperatures of over 50°C. Its altitudinal range is from 0—1200 m. It is fairly tolerant of shade, at least when young. Annual rainfall required is 500—2500 mm, with a dry season of 2—6 months. It occurs naturally in lowland forest on limestone and rocky coral outcrops on the coast, along the edges of mangrove forest and along tidal streams and rivers. Best growth is found on deep sandy loams, but it will also grow on sandy soils and heavy swelling clay soils. It is very tolerant of saline conditions and tolerant of alkalinity.

Pongamia pinnata can easily be propagated by seed and cuttings. Even branches stuck in moist soil develop roots readily. Seed remains viable for a long time. No seed treatment is required. Germination takes 10 days to 1 month. In the nursery, it can be planted at a close spacing and tolerates shade well. In India, a spacing of 7.5 cm x 15 cm is recommended. Seedlings reach a height of 60 cm about 1.5 years after sowing and are easy to transplant. Direct sowing is common and mostly successful. Trees coppice well and can also be pollarded. Spontaneous seedlings and root suckers are produced in large numbers and may create serious weed problems. Pongamia pinnata is host to a large number of fungi and insects, but serious damage has not been reported. Pod production starts 5—7 years after sowing. Individual trees yield 9—90 kg of pods annually. Ripe pods are collected in India from April—June and are subsequently dried in the sun. Seeds are easily extracted by light hammering or by splitting the pod with a knife along the sutures and winnowing out of the husks. Mature trees yield 8—24 kg seed annually.

No germplasm collections or breeding programmes are known to exist.

Pongamia pinnata is likely to remain important as a reforestation and fuelwood tree because of its adaptability to poor and saline soils, its many useful products and ease of planting. More research attention to develop its potential as insecticide and as medicine seems warranted.

Axtell, B.L. & Fairman, R.M., 1992. Minor oil crops. FAO Agricultural Services Bulletin 94. Food and Agriculture Organization of the United Nations, Rome, Italy. pp. 153-155.
Morton, J.F., 1991. The pongam tree, unfit for Florida landscaping, has multiple practical uses in under-developed lands. Proceedings of the Florida State Horticultural Society 103: 338-343.
National Academy of Sciences, 1980. Firewood crops. Shrub and tree species for energy production. Vol. 1. National Academy Press, Washington, D.C., United States. pp. 42-43.
Philip, E. & Syed, S.B., 1994. Leaffall patterns of Pongamia pinnata in two different sites: A preliminary observation. Transactions of the Malaysian Society of Plant Physiology 5: 189-191.
Singh, M.P., Jain, B.P., Srivastava, J.L. & Trivedi, R.N. (Editors), 1991. Nitrogen fixing and multipurpose tree species for afforestation. Today and Tomorrow's Printing & Publishers, New Delhi, India. pp. 192-195.
Verdcourt, B., 1979. A manual of New Guinea legumes. Botany Bulletin No 11. Office of Forests, Division of Botany. Lae, Papua New Guinea. pp. 311-314.

L.P.A. Oyen

Oyen, L.P.A., 1997. Pongamia pinnata (L.) Pierre. In: Faridah Hanum, I & van der Maesen, L.J.G. (Editors): Plant Resources of South-East Asia No 11: Auxiliary plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea