Solanum torvum (PROSEA)
Solanum torvum Swartz
- Protologue: Nov. gen. sp. pl. prodr.: 47 (1788).
- Family: Solanaceae
- Chromosome number: 2n= 24, 48
- Solanum ferrugineum Jacq. (1798),
- S. largiflorum C. White (1917).
- Devil's fig, plate brush (En)
- Indonesia: takokak, pokak (Javanese), terong pipit (Sumatra)
- Malaysia: terong pipit, terong rembang
- Papua New Guinea: podopodo kai ra ta ba rau (New Britain, Kuanua)
- Philippines: takapasin (Tagalog), taogotan (Bisaya), balbalusa (Bontoc)
- Laos: kh'èèngz f'aaz, kh'èèngz saph'au
- Thailand: makhua-phuang (general), ma-khwaeng (northern)
- Vietnam: cà dại hoa trắng, cà hoang.
Origin and geographic distribution
S. torvum originates from the Antilles, but is now a pantropical weed. Occasionally it is also cultivated, especially in South, South-East and East Asia.
Young, immature fruits are eaten raw or cooked as vegetable or are used as an ingredient in curry sauce. In Indonesia S. torvum is considered one of the best vegetable side-dishes with rice.
In traditional medicine, various uses are reported: roots for poulticing cracks in the feet (Malaysia) or as an antitussive in China where they are believed to disperse extravasated blood and to relieve pain; seeds are smoked in Malaysia for curing toothache; in India extracts of the plant are used as antidote to snakebite and insect stings, and fruits are eaten to relieve stomach pain.
S. torvum is sometimes used as a rootstock for tomato (Brunei) to resist bacterial wilt, and for eggplant (Japan, Trinidad) and for S. quitoense Lamk (Colombia, Ecuador).
Production and international trade
No statistics are available. Fruits are mainly gathered from wild plants or from plants cultivated in home gardens; they are consumed and marketed locally. It is common in the vegetable assortment of large supermarkets.
Per 100 g edible portion, young fruits contain: water 89 g, protein 2 g, fat 0.1 g, carbohydrates 7.9 g, Ca 50 mg, P 30 mg, Fe 2 mg, vitamin A 750 IU, vitamin B1 0.08 mg, vitamin C 80 mg. The energy value is 160 kJ/100 g.
The steroidal alkaloid solasodine, which is used in the manufacture of steroidal sex hormone for oral contraceptives, is present (0.84%) in the leaves and fruits.
In tropical pastures, S. torvum can be a troublesome weed. In Australia it is suspected of poisoning livestock; in Papua New Guinea it is suspected to be a causal agent of enzootic calcinosis in cattle.
- A spreading or scrambling slender shrub, up to 3 m tall, pubescent with stellate hairs.
- Prickles scattered on stem, branches and leaves, especially in younger growth, 3-7 mm long, slightly hooked.
- Leaves alternate, solitary or in pairs, variable; petiole 1.5-5 cm long; leaf-blade ovate, 7-20 cm × 4-18 cm, coarsely, sinuously 7-lobed; base equal or unequal, somewhat sagittate to auriculate; lobes triangular, 3-4 cm long, acute or obtuse.
- Inflorescence a compact, branched, 50-100-flowered corymb, at first terminal, later becoming lateral and markedly supra-axillary; peduncle 1-2 cm long; pedicel 0.5-1 cm long, slightly elongating and thickening in fruit; flowers hermaphrodite, upper ones may be male; calyx 5-lobed, 3-4 mm long, persistent; corolla stellate, 2.5 cm in diameter, white, lobes 5, lanceolate, 1 cm long; stamens 5, inserted on corolla throat, anthers attenuate, 6-7 mm long on very short filaments; ovary globose, pubescent, style 8-10 mm long.
- Fruit a globular berry, 1-1.5 cm in diameter, yellowish, glabrous, produced in clusters of few to 10.
- Seeds 300-400 per fruit, flat, 1.5-2 mm long, brownish.
S. torvum flowers throughout the year, but relatively few flowers set fruit. Heavy rainfall also discourages fruit set. Plants are said to have an economic lifetime of 3-4 years. The large variability within the species has led to various classifications, but no strict lines can be drawn between the distinguished taxa. The correctness of the name S. torvum is still subject of discussion. Some authors consider S. ficifolium Ortega as the correct name for this taxon. No cultivar names have yet been employed for cultivated forms.
S. torvum is a common pantropical weed, common along roadsides and in waste places after soil disturbance, usually as individual plants. In cultivated fields it is not usually a troublesome weed. It prefers moist, but not too wet places, and occurs up to 1600 m altitude.
S. torvum is easily propagated by seed, but can also be propagated by separating rooted shoots. In South-East Asia it is usually planted in home gardens, at distances about 1.5-2 m square. Instead of being cultivated it is often only spared if it grows naturally. S. torvum has no serious diseases or pests. In India a leaf-spot (Alternaria solani) and a shoot and fruit borer (Leucinodes orbonalis) have been reported. It is susceptible to nematodes (Meloidogyne spp.); in cultivation a rotation scheme can avoid problems.
The fruits are harvested when still immature.
Genetic resources and breeding
No substantial germplasm collections or breeding programmes for its own improvement exist as far as is known. Its importance for breeding is its resistance to Verticillium wilt; attempts are being made to incorporate this character in more important solanaceous crops. S. torvum is used as a rootstock for other crops.
S. torvum is considered a good vegetable, and deserves more research attention. Its major significance at present is as a rootstock and as a source of resistance against diseases and pests for economically more important solanaceous crops.
- Backer, C.A. & Bakhuizen van den Brink Jr, R.C., 1965. Flora of Java. Vol. 2. Wolters-Noordhoff, Groningen, the Netherlands. p. 475.
- Hepper, F.N., 1987. Solanaceae. In: Dassanayake, M.D. & Fosberg, F.R. (Editors): A revised handbook to the flora of Ceylon. Vol. 6. Amerind Publishing Company, New Delhi, India. pp. 376-378.
- Ochse, J.J. & Bakhuizen van den Brink, R.C., 1980. Vegetables of the Dutch East Indies. 3rd English edition (translation of "Indische Groenten", 1931). Asher & Co., Amsterdam, the Netherlands. pp. 685-686.
- Symon, D.E., 1981. A revision of the genus Solanum in Australia. Journal of the Adelaide Botanic Gardens 4: 115-116.
- T. Boonkerd, B. Na Songkhla & W. Thephuttee