Lactuca indica (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Lactuca indica L.

Protologue: Mant. pl. 2: 278 (1771).

Family: Compositae

Chromosome number: 2n= 18

Synonyms

• Lactuca brevirostris Champ. ex Benth. (1852).

Vernacular names

• Indian lettuce (En)
• Indonesia: komak, lampenas (Sundanese), sawi rana (Javanese)
• Malaysia: daun panjang
• Philippines: gilgiloy (Bisaya), batudan (Bontoc), gatudan (Kankanai)
• Vietnam: diếp dại, rau bồ cóc, bồ công anh.

Origin and geographic distribution

L. indica is native to the warmer parts of China, Taiwan, and southern Japan, where it occurs wild and cultivated. It has been introduced into South-East Asia, probably by Chinese immigrants, and is relatively common in Indonesia and Malaysia, where it sometimes occurs as an escape from cultivation.

Uses

Indian lettuce is grown for its leaves. They are consumed raw, boiled or steamed. Leaves are also used for wrapping and frying fish. Furthermore, the leaves are considered tonic, digestive and depurative in traditional medicine. In Taiwan it is grown as feed for geese. Silkworm can be fed with the leaves as a substitute for mulberry.

Production and international trade

Indian lettuce is grown for local consumption on a small scale. It is fairly common in the mountainous areas of Puncak and Bandung (West Java, Indonesia) and in the Cameron Highlands (Malaysia). It is also commonly grown as a barrier crop in vegetable farms in the lowlands of Malaysia. No statistics are available.

Botany

• Perennial, erect, tillering, laticiferous herb, with radical rosette when young, up to 2 m tall when flowering.
• Leaves alternate, sessile, oblong-lanceolate, very variable in shape and dimension, with narrowed base and acute apex, 5-35 cm × 1-10 cm, often with a red midrib.
• Inflorescence terminal, paniculiform or corymbiform, 50-100 cm long, many-branched, with numerous relatively small (2 cm × 5-7 mm) flower heads; involucral bracts partly ovate (outer ones), partly oblong-linear-lanceolate (inner ones); flowers ligulate, bright yellow, patent or obliquely erect.
• Fruit a flat elliptical achene, 3-4 mm × 2 mm, black, shortly beaked, hard, at the top with a tuft of white hairs. Mature plants produce basal shoots.

In Taiwan and Japan, several forms differing mainly in leaf-form have been distinguished as botanical varieties or formas. The leaves vary from undivided linear-lanceolate to deeply pinnatifid oblong.

Ecology

Indian lettuce is cultivated from the lowlands up to 2000 m altitude. Sometimes it grows wild as an escape from cultivation in ravines, waste places, field and forest borders, roadsides, and plantations of perennial crops. It prefers fertile, well-drained soils with a high organic matter content, but tolerates a wide range of soils.

Agronomy

Propagation is by seed, which germinate 3-4 days after sowing, or by root cuttings, which easily develop buds. Seeds are usually sown on a seed-bed and seedlings transplanted when they are 5-10 cm tall, 3-4 weeks after sowing. Cultivation methods are similar to lettuce (L. sativa L.). Indian lettuce can be planted in field beds at a spacing of 30 cm × 30 cm. Because of its tall stature it is often planted in the middle of field beds to provide light shade for other vegetables. It is commonly grown on dikes of rice fields and in home gardens.

Cucumber mosaic virus (CMV) may cause stunted growth, reducing leaf quality.

When plants are about 2 months old and 50 cm tall, harvesting of individual leaves starts and continues until flowering interferes. Plants may then be cut near ground level for axillary buds to form a ratoon crop.

Genetic resources and breeding

Some accessions of L. indica are usually maintained in germplasm collections of lettuce (L. sativa) and related species, but there are no specific collections for Indian lettuce.

There are clear breeding barriers between the "sativa-serriola" and "indica" group.

Prospects

Indian lettuce has maintained a niche in the market beside more productive salad crops. Very little information on this crop exists and that alone is sufficient reason for more research attention.

Literature

• Herklots, G.A.C., 1972. Vegetables in South-East Asia. George Allen & Unwin, London, United Kingdom. pp. 137-138.
• 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. 135-137.
• Simmonds, N.W. (Editor), 1976. Evolution of crop plants. Longman, London, United Kingdom. pp. 39-41.

Authors

• Roemantyo