Limnocharis flava (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Limnocharis flava (L.) Buchenau

Protologue: Abh. Naturw. Ver. Bremen 2: 2 (1868).

Family: Butomaceae

Chromosome number: 2n= unknown

Synonyms

• Alisma flava L. (1753),
• Limnocharis emarginata Kunth (1807),
• L. plumieri Richard (1815).

Vernacular names

• Sawah lettuce, velvet leaf, hermit's waterlily (En)
• Indonesia: genjer, bangeng, eceng
• Malaysia: emparuk (Sarawak), jinjir, paku rawan
• Laos: kaanz choong
• Thailand: bon-chin (southern), talapatrusi (central), nangkwak (central)
• Vietnam: kèo nèo, nê thảo.

Origin and geographic distribution

L. flava is native to tropical and subtropical America and was introduced into South-East Asia more than a century ago. Now it occurs naturalized in Indonesia (Java, Sumatra), Malaysia, Thailand, Burma and Sri Lanka.

Uses

Young leaves with petioles and young, unopened inflorescences are eaten as a vegetable in Indonesia, especially West Java, in Malaysia and in Thailand. Usually they are not eaten raw but heated above a fire or cooked for a short time. The older leaves have a bitter taste. Whole plants are given as fodder to pigs or fish. L. flava also serves as an ornamental plant in ponds. Plants are often ploughed in as green manure in rice fields.

Production and international trade

In West Java L. flava is a common vegetable in markets and supermarkets but data on production are rare. In an integrated system of pisciculture and genjer cultivation, an Indonesian farmer harvested about 1000 bunches/ha in 3 months (1 bunch = 20 sprouts).

Properties

Per 100 g edible portion L. flava contains: protein 1 g, fat 0.3 g, carbohydrates 0.5 g, vitamin A 5000 IU and vitamin B₁ 10 IU. The energy value is 38 kJ/100 g.

Botany

• A perennial, erect, laticiferous, aquatic to swampy-terrestrial herb, 20-100 cm tall, strongly tillering.
• Leaves in a basal rosette, glabrous; petiole 5-75 cm long, thick, trigonous with many air chambers, sheathing at the base; leaf-blade orbicular, broad elliptic or ovate, 5-30 cm × 4-25 cm, yellow-green; nervation characteristic, main nerves 9-13 with numerous transverse parallel running secondary nerves.
• Inflorescence umbelliform, 3-15-flowered, peduncle up to 90 cm long, erect when flowering, downcurved when fruiting; flowers in the axils of membranous bracts; pedicel 2-7 cm long; sepals 3, ca. 2 cm long; petals 3, ovate to orbicular, 1.5-3 cm long, yellow; stamens more than 15, surrounded by a whorl of staminodes; ovaries 10-20.
• Fruit compound, composed of the ripe carpels forming together a globose or broadly ellipsoid body of 1.5-2 cm in diameter, enclosed by the sepals. Seed horseshoe-shaped, 1-1.5 mm long, provided with transverse crests, dark brown.
• Seedling with one, 8-11.5 mm long cotyledon, sheathing around the first leaf.

L. flava flowers the whole year round. The flowers open in the morning and close after a few hours. There is no record of any pollinating agent. After anthesis the sepals enlarge and surround the fruit whereas the petals become a slimy mass. When ripe the fruit carpels fall into the water where they release the seeds, which sink to the bottom. The downturned inflorescence which rests on the water surface often produces a new plant.

Ecology

L. flava grows in marshy, shallow locations like rice fields, (fish) ponds and ditches up to 1300 m altitude.

Agronomy

L. flava can be cultivated the whole year round. It is propagated by layers, but propagation by seed is also possible. It needs a fertile soil; 1-2 weeks before planting, the soil should be enriched with organic fertilizer (10 t/ha). Planting distance is about 30 cm square. In a fertile sawah it will grow very fast and the leaves and inflorescences can be harvested after 2-3 months. If not harvested regularly the plant population will soon become too dense and should be renewed to maintain quality. After harvesting, the leaves and inflorescences are bundled together or separately and sold in small bunches.

Prospects

L. flava is one of the most relished local vegetables of West Java and is also popular in Thailand; it deserves more attention in other areas. There is little information on this species. Cultivation in an integrated pisciculture system seems to be a good practice.

Literature

• Djajadiredja, R. & Jangkaru, Z., 1979. Small scale fish/crop/livestock home industry integration. A preliminary study in West Java. Indonesian Agricultural Research & Development Journal 1(3/4): 1-4.
• 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 and Co., Amsterdam, the Netherlands. pp. 88-90.
• Soedirdjoatmodjo, M.D.S. 1986. Bertanam sayur daun [Growing leafy vegetables]. B.P. Karya Bani, Jakarta, Indonesia. pp. 43-46.
• Soerjani, M., Kostermans, A.J.G.H. & Tjitrosoepomo, G., 1987. Weeds of rice in Indonesia. Balai Pustaka, Jakarta, Indonesia. pp. 118-119, 592-593.
• van Steenis, C.G.G.J., 1954. Butomaceae. In: van Steenis, C.G.G.J. et al. (Editors), 1950- . Flora Malesiana. Series I. Vol. 5(1). Noordhoff-Kolff, Djakarta, Indonesia. pp. 118-120.

Authors

• M.H. van den Bergh