Indigofera suffruticosa (PROSEA)
Indigofera suffruticosa Miller
- Protologue: Gard. Dict. ed. 8, No 2 (1768).
- Family: Leguminosae - Papilionoideae
- Chromosome number: 2n = 12, 16
- Indigofera anil L. (1771).
- Anil indigo (En). Anil de pasto (Am).
- Indonesia: taem-taem (Sumatra), tagom-tagom (Kalimantan), tom janti (Javanese).
- Malaysia: tarom, sekebak (Peninsular Malaysia).
- Philippines: tina-tinaan (Tagalog), tayum (Bisaya, Ilokano), sangifaria (Mindanao).
- Thailand: khram-thuan (Shan, Chiang Mai), khram yai (Ubon Ratchathani).
- Vietnam: chàm bụi, cây chàm.
Origin and geographic distribution
I. suffruticosa originated in tropical America, but is now widely distributed and naturalized throughout the tropics, including South-East Asia.
I. suffruticosa is used mainly in Java and Sri Lanka as a cover crop and green manure in coffee, rubber and tea plantations. In South America it is one of the components of natural pastures developing after clearing rain forest. It has been widely cultivated as a dye plant yielding indican from which indigo is prepared. Its cultivation for local use still continues on a small scale. In Malaysia a decoction of the roots is taken against stomach-ache, an infusion of bruised leaves against fever and plant juice against diarrhoea. In China a mixture of the leaves of I. suffruticosa, I. tinctoria L., the bark of Phellodendron chinense C.K. Schneider and pig bile is used as a medicine against scrofula.
Production and international trade
I. suffruticosa is still grown for dye on a very small scale in Java, Karnataka (India), Africa and Central America, but no statistics exist.
In Hawaii fresh material of I. suffruticosa grown as a green manure has a nitrogen content per 100 g dry matter of 1.6-3.1 g in the above-ground parts, and 1.4-2.4 g in the roots.
Plants contain the glucoside indican, which transforms into indoxyl (indigo-white) and glucose by enzymatic hydrolysis. Indoxyl can be oxidized to indigo-blue. An aqueous extract of the fruit has an hepatotoxic effect and causes chromosome aberrations in mice.
The weight of 1000 seeds is about 4 g.
- Shrub, 45-250 cm tall with erect, striate branches and with indumentum of appressed, biramous hairs with equally long arms.
- Leaves imparipinnate; stipules narrowly triangular, 3-6 mm × 0.2-0.3 mm; petiole up to 2 cm long; rachis 5-10 cm long; petiolule 1-1.5 mm long; stipels linear; leaflets opposite, (7-)9-15, narrowly elliptical to narrowly obovate, 10-40 mm × 3-15 mm, base cuneate, apex acute to rounded, mucronate, glabrous or with very few hairs above, appressed grey pubescent beneath.
- Inflorescence an axillary raceme, 2-6 cm long; bracts narrowly triangular; pedicel 0.5-1 mm long.
- Flower 4-5 mm long, salmon pink to red; calyx campanulate, tube 1 mm long, teeth triangular, 0.7-1.2 mm long; standard ovate to orbicular, 3-4.5 mm × 2.5-3 mm, hairy on the back; wings 2-4 mm × 0.8-1.2 mm, glabrous; keel 2.5-4.5 mm × 1.2-2 mm, hairy, margins not ciliate, lateral pocket 0.5 mm long; stamens 10, 1 free, 9 connate into a staminal tube 3.5-4 mm long; ovary hairy, style with capitate stigma.
- Fruit a descending pod, 4-6-seeded, distinctly upcurved, 1.5-2(-3) cm × 2 mm, hairy. Seed cubical, 1.5-2.0 mm × 1.5 mm, shiny brown.
- Seedling with epigeal germination.
Growth and development
The first leaves formed after germination are simple. Seedlings quickly develop a deep root system. I. suffruticosa may occasionally overgrow young tea plants, but can be removed very easily as it neither winds nor climbs. Flowering starts early, at an age of 4-5 months. After 4-5 loppings in 2-2.5 years, plants tend to die out.
Other botanical information
Two subspecies are recognized in I. suffruticosa: subsp. suffruticosa and subsp. guatemalensis (Mocino, Sessé & Cerv. ex Backer) de Kort & Thijsse (synonym: I. guatemalensis Mocino, Sessé & Cerv. ex Backer). Subsp. guatemalensis occurs naturalized in Thailand and Vietnam and is cultivated in Java where it is sometimes adventive, but where it does not naturalize; it can be distinguished by its smaller leaves and flowers (to 3 mm long) and straight, 1-3-seeded pods; its branches are not striate. I. suffruticosa closely resembles I. arrecta Hochst. ex A. Rich. (taller, less bushy and always with straight pods) and I. tinctoria L. (smaller, pods smaller, straight or slightly curved, 7-12-seeded). It is possible that these 3 species sometimes hybridize.
I. suffruticosa is commonly found on roadsides, waste land, fallow land and cultivated fields up to 1800 m altitude. It is sometimes found on beaches and in grass fields.
Seed and stem cuttings are used for propagation. Sowing is done either in seed-beds or directly into the field. Seed should be soaked in water overnight for optimal germination. In direct planting seeds are sown in continuous lines about 30 cm apart or 3-4 together in holes 45 cm × 60 cm apart. Germination takes 4-6 days. When a seed-bed is used the seedlings can be transplanted 4-6 weeks after sowing. Cuttings are taken from well developed branches divided into 30 cm long pieces. They are kept for 2-3 days in a cool place before planting out, 2-3 per hole. Rooting starts in the second week.
After sowing or planting, weeding is necessary. In I. suffruticosa cover crops, weeding is mostly done selectively. Some weeds are left like Centella asiatica (L.) Urb. and Drymaria glandulosa Bartl. as they also are valuable cover plants and help in checking erosion. Lopping can be started when the plants have a height of 50 cm, leaving about 25 cm. A good cover of I. suffruticosa can increase the nitrogen content of the soil considerably. In Sri Lanka for example, an increase from 3.7% to 5.3% in 4 years was found.
Diseases and pests
No serious diseases or pests have ever been reported to attack I. suffuticosa. In humid conditions Corticium salmonicolor sometimes affects the stems after slashing.
Genetic resources and breeding
Polyploid strains of I. suffruticosa seem to exist. A collection of Indigofera germplasm is being maintained at the Southern Regional Plant Introduction Station of the United States Department of Agriculture, Griffin, Georgia, which includes several accessions of I. suffruticosa.
I. suffruticosa forms in a short period a dense and well-rooted soil cover and is an excellent cover crop that deserves more attention from research and extension.
- Chow, K.H., 1976. Morphology and ecology of some wild herbaceous legumes in Singapore. Journal of the Singapore National Academy of Science 5: 20-30.
- de Kort, I. & Thijsse, G., 1984. A revision of Indigofera in South-East Asia. Blumea 30: 89-151.
- Lemmens, R.H.M.J. & Wessel-Riemens, P.C., 1991. Indigofera L. In: Lemmens, R.H.M.J. & Wulijarni-Soetjipto, N. (Editors): Plant Resources of South-East Asia No 3: Dye and tannin-producing plants. Pudoc, Wageningen, the Netherlands. pp. 81-83.
- Rembert, D.H., 1979. The indigo of commerce in colonial North America (Indigofera caroliniana, Indigofera tinctoria, Indigofera suffruticosa). Economic Botany 33: 128-134.
- Ribeiro, L.R., Bautista, A.R.P.L., Silva, A.R., Sales, L.A., Salvadore, D.M.F. & Maia, P.C., 1991. Toxicological and toxicogenetic effects of plants used in popular medicine and in cattle food. Memorias do Instituto Oswaldo Cruz 86, Suppl. 2: 89-91.
- Sanjappa, M., 1987. The Indigoferas of Sri Lanka. Journal of Economic and Taxonomic Botany 10: 329-346.
- B. Sunarno