Prota 2: Vegetables/Légumes
Sp. pl. ed. 2, 2: 1405 (1763).
2n = 34
Amaranthus gracilis Desf. ex Poir. (1810).
Green amaranth, local tete, African spinach (En). Amarante verte, épinard vert, épinard du Congo (Fr). Amaranto (Po). Mchicha (Sw).
Origin and geographic distribution
Amaranthus viridis is possibly of Asian origin but now a cosmopolitan weed in the tropical and subtropical regions of the world, also penetrating far into temperate regions (e.g. in Europe, North America, Asia and Australia). In tropical Africa it is also a widespread and common weed. It is occasionally cultivated (e.g. in Nigeria, Gabon and DR Congo).
Amaranthus viridis leaves and young plants (before they come into flower) are occasionally eaten as a cooked vegetable. The plant is also a good cattle fodder and green manure. The leaves are diuretic and purgative, and are used in poultices (fresh or as dried powder) to treat inflammations, boils and abscesses, gonorrhoea, orchitis and haemorrhoids. In Nigeria an infusion of the whole plant is used to purify the blood and the pounded root is applied against dysentery. In Côte d’Ivoire leaf sap is used as an eye wash to treat eye infections and for treating convulsions and epilepsy in children. In DR Congo the sap is said to act as a vermifuge, being effective against filaria, as an emmenagogue and to relieve heart troubles. The leaves are believed to have febrifugal properties. Ash of Amaranthus viridis plants is rich in soda and is occasionally used to make soap.
The composition of the leaves of Amaranthus viridis is comparable to that of other Amaranthus species, e.g. Amaranthus cruentus L. The (powdered) leaf contains tannin, reducing sugar and resin. Amasterol (24-methylene-20-hydroxycholest-5,7-en -3β-ol) has been isolated from the roots; this compound has allelopathic effects on lettuce seed germination.
Erect or ascending annual or short-lived perennial herb up to 1 m tall; stem slender, branched, angular, glabrous to sparsely pubescent in upper part with multicellular hairs. Leaves alternate, simple; petiole up to 10 cm long; blade deltoid-ovate to rhomboid-oblong, 2–8 cm × 1.5–6 cm, base shortly cuneate, apex emarginate with small mucro, margin sometimes sinuate, glabrous to pubescent. Inflorescence consisting of agglomerated cymes arranged in slender, axillary or mostly terminal spikes, frequently paniculate, up to 12 cm long, in the lower part of the stem often in dense axillary clusters c. 7 mm in diameter. Flowers unisexual, subsessile, green, male and female intermixed but female ones more numerous; bracts and bracteoles lanceolate-ovate, c. 1 mm long, whitish-membranous; tepals 3, oblong to obovate, 1–1.5 mm long, midrib often thickened above, bent along the fruit; male flowers with 3 stamens; female flowers with superior, 1-celled ovary crowned by 2–3 short stigmas. Fruit a subglobose capsule, c. 1.5 mm in diameter, not or slightly exceeding the perianth, indehiscent, usually strongly wrinkled, 1-seeded. Seed subglobose, slightly compressed, c. 1 mm in diameter, margin acute, glossy black, verrucose or with inconspicuous sculpture. Seedling with epigeal germination; cotyledons lanceolate, c. 12 mm × 2.5 mm.
Amaranthus comprises about 70 species, of which about 40 are native to the Americas. It includes at least 17 species with edible leaves and 3 grain amaranths. Amaranthus viridis is often confused with Amaranthus blitum L., but the latter differs in its often more ellipsoid and smooth or slightly wrinkled fruits. It is sometimes also confused with Amaranthus deflexus L., a perennial herb with prostrate or ascending stems originating from temperate South America, but now naturalized as a weed in many parts of the world, locally also in tropical Africa (e.g. Kenya, Zimbabwe). In South Africa Amaranthus deflexus is sometimes used as a cooked vegetable.
In Africa Amaranthus viridis is a weed growing on disturbed or cultivated land, often around habitations. It flowers and fruits year-round.
Although mostly collected from the wild, Amaranthus viridis is easily grown from seed like other amaranths. Pigweed mosaic virus causes shorter shoots, roots and inflorescences, smaller leaves and stem diameter, less branching and a reduction of the fresh weight of shoots and roots.
Genetic resources and breeding
A collection of amaranths is kept at the Rodale Organic Gardening and Farming Research Center (OGFRC) at Kutztown, Pennsylvania, United States; South-East Asian accessions are kept at the Asian Vegetable Research and Development Center (AVRDC) at Tainan, Taiwan. African cultivars and introductions from OGFRC are kept at the National Horticultural Research Institute (NHR) in Nigeria and African cultivars at the AVRDC centre at Arusha, Tanzania. Indian collections are kept at the National Bureau of Plant Genetic Resources (NBPGR), New Delhi, India. Many national institutes have small working collections of local cultivars. Evaluation and variability studies are needed to reveal the amount of exploitable genetic variation.
Amaranthus viridis is an interesting weed vegetable with a good nutritional value. It certainly deserves more attention to determine wider domestication possibilities and optimum cultivation practices. Its medicinal properties need further investigation as well.
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Correct citation of this article:
Jansen, P.C.M., 2004. Amaranthus viridis L. In: Grubben, G.J.H. & Denton, O.A. (Editors). PROTA 2: Vegetables/Légumes. [CD-Rom]. PROTA, Wageningen, Netherlands.