| Root crops |
Sagittaria sagittifolia L.
Beea beea (Mal.); Chee-koo (China); Chotakut (Ind.); Duck potato, Echtes (Ger.); FlÃ¨che d'eau, FlÃ©chiÃ¨re (Fr.); GÃ¡uai-gÃ¡uai (Philipp.); Kuwai (Japan); MuyÃ¡-muyÃ¡ (Ind.); Pfeilkraut (Ger.); Pijkruid (Nether.); Sagittaire (Fr.); Swamp or Swan potato, T'zu ku (China).
A perennial robust, aquatic plant, from 0.6 to 1.2 m tall, with smooth, broad sagittate leaves, raised above the water level, as is the erect inflorescence, which is long-peduncled, glabrous, racemose, simple or branched. The flowers are whorled, usually white, sometimes with a purple spotted base. The carpers are flat and crowded into a globular head. Each plant produces 4-6 small subterranean tuberous rhizomes at the base of the erect stem.
Origin and distribution
The arrowhead is believed to be a native of the more temperate parts of China but has now spread to tropical and subtropical parts of Asia. A closely related species, S. latifolia Willd., is native to North America, and there may be some confusion between the species in the literature. Arrowhead is an aquatic plant and is found growing wild or in a semi-wild state in the marshes and lakes of China, Japan, India, Malaysia, the Philippines and certain islands in the Pacific.
The plant will thrive in wet or marshy places in a range of climates from tropical to warm temperate. Where cultivation is undertaken it is often similar to that used for rice.
Material-propagation is vegetative using pieces of corm with an axilliary bud.
Method-arrowhead is easily established. In some countries the field preparation is similar to that used for rice or lowland tarot This involves ploughing, discing and harrowing to level the surface and providing a well-puddled soil suitable for flooding, into which the pieces of corm are set by hand at a depth of about 20 cm.
The corms mature in about 6-7 months.
Harvesting and handling
The corms are dug by hand.
Corms-the starchy corms are hard, with a globular base and an acute apex, approximately 5 cm in diameter, covered with whitish or bluish-white scales, which quickly wither to expose creamy-white or buff flesh, which exudes a milky juice when cut. Each corm weighs about 15-30 g.
The corms are used as a starchy vegetable after boiling and are a constituent of several Japanese and Chinese meat dishes. In the USA they were formerly much used by Indians, but apparently are now seldom employed as human food in that country, except by some ethnic minorities.
The tubers are sometimes employed as a source of starch in China, or for pig-feed. The plant has also been used medicinally for skin diseases and in childbirth.
Secondary and waste products
The young leaves are sometimes eaten as a green vegetable and are also used for medicinal purposes in China.
The composition of the edible portion of the corms has been published as: energy 448 kJ/100 g; water 70.6 per cent; protein 5 per cent; fat 0.3 per cent; carbohydrate 22.4 per cent; fibre 0.9 per cent; calcium 13 mg/100 g; iron 2.6 mg/100 g; phosphorus 165 mg/100 g; potassium 729 mg/100 g; thiamine 0.16 mg/100 g; riboflavin 0.04 mg/100 g; niacin 1.4 mg/100 g; ascorbic acid 5 mg/100 g.
The carbohydrate consists mainly of starch with about 2 per cent of sucrose. The starch grains are large, round, oval or rounded-angular, with a diameter of up to 30-36 microns. An anti-inflammatory principle, sagittariol, occurs in the plant.
CHUNG, H. L. and RIPPERTON, J. C. 1929. Utilization and composition of oriental vegetables in Hawaii. United States Department of Agriculture, Hawaii Agricultural Experiment Station Bulletin, No. 60, 45-46.
LERMAN, M. H. 1980. Arrowhead or duck potato. Minnesota Horticulturist, 108 (7), 207.
OCHSE, J. J. 1931. Sagittaria sagittifolia L. Vegetables of the Dutch East Indies, pp. 8-10. Buitenzorg-Java: Archipel Drukkerij, 1005 pp.
PORTERFIELD, W. M. 1940. The arrowhead as a food among the Chinese. Journal of the New York Botanic Garden, 41, 45-47.
PORTERFIELD, W. M. (Jr.) 1951. The principal Chinese vegetable foods and food plants of Chinatown markets. Economic Botany, 5, 16-18.
SHARMA, S. C.,TANDON, J. S. and DHAR, M. M. 1975. Sagittariol; a new diterpene from Sagittaria sagittifolia. Phytochemistry, 14, 1055-1057.
SHERMAN, H. E. and WANG, C. T. 1929. Chemical analyses of thirty-seven oriental foods. Philippine Journal of Science, 38, 69-79.