Polygonum plebeium (PROTA)

Plant Resources of Tropical Africa Introduction

List of species

General importance
Geographic coverage Africa
Geographic coverage World
Vegetable
Medicinal
Forage / feed
Food security

Polygonum plebeium R.Br.

Protologue: Prodr.: 420 (1810).

Family: Polygonaceae

Chromosome number: 2n = 20

Synonyms

Polygonum herniarioides Delile (1813), Polygonum roxburghii Meisn. (1856).

Vernacular names

Small knotweed (En).

Origin and geographic distribution

Polygonum plebeium is widespread all over tropical Africa, Asia and Australia. In some regions it is rare (e.g. DR Congo).

Uses

Polygonum plebeium is eaten as a vegetable in Malawi, cooked with potatoes and groundnuts. The product is slimy but well liked because it has a good smell. In India it is used as a famine vegetable, and it is grazed by horses. In Australia crushed seeds are cooked and eaten against bowel complaints; in India the roots are similarly applied.

Properties

Dry Polygonum plebeium leaves contain per 100 g dry matter: protein 17 g, fat 3 g, carbohydrate 50 g, fibre 16 g, P 0.3 g (Hooper, D., 1904). When grown in dry places the leaves are said to be bitter. The fresh root contains 11% tannin, and oxymethylanthraquinone has also been isolated.

Botany

Prostrate annual herb, much-branched, glabrous; stems up to 35 cm long, scabrid, red-brown, with short internodes. Leaves alternate, simple; ocrea cylindrical, up to 3 mm long, often silvery-white, irregularly fringed; petiole very short; blade very small, linear to obovate-elliptical, 1–2 cm × 2–5 mm, margin revolute, rather thick and leathery, dark green turning red. Inflorescence a congested raceme with short branches, forming axillary, 1–5-flowered clusters. Flowers bisexual; perianth 2 mm long, greenish, with 4 lanceolate-elliptical lobes 1.5 mm long, the outer pair keeled, white to pale pink; stamens 5–8; ovary superior, 1-celled, styles 3, free, 3 mm long. Fruit a trigonous nut up to 2 mm long, smooth, shiny black.

Ecology

Polygonum plebeium occurs in drier locations than many other Polygonum species, such as rocky ground in dried riverbeds and drying mudflats along lakes, in eastern Africa usually at 600–2400 m altitude. It also grows as a weed in fields.

Management

Polygonum plebeium is collected from the wild and is not cultivated.

Genetic resources

Polygonum plebeium is very widespread and is not in danger of genetic erosion.

Prospects

Polygonum plebeium will remain a locally important vegetable, particularly in times of scarcity. Its nutritive and medicinal properties need more research.

Major references

• Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Volume 4, Families M–R. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 969 pp.

• Graham, R.A., 1958. Polygonaceae. In: Turrill, W.B. & Milne-Redhead, E. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 40 pp.

• Williamson, J., 1955. Useful plants of Nyasaland. The Government Printer, Zomba, Nyasaland. 168 pp.

Other references

• Hedberg, O., 2000. Polygonaceae. In: Edwards, S., Mesfin Tadesse, Demissew Sebsebe & Hedberg, I. (Editors). Flora of Ethiopia and Eritrea. Volume 2, part 1. Magnoliaceae to Flacourtiaceae. The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. pp. 336–347.

• Hooper, D., 1904. Analyses of Indian pot-herbs of the natural orders Amarantaceae, Chenopodiaceae, and Polygonaceae. Agricultural Ledger (Calcutta) 6: 423–434.

• Keay, R.W.J., 1954. Polygonaceae. In: Keay, R.W.J. (Editor). Flora of West Tropical Africa. Volume 1, part 1. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 137–142.

• Robyns, W., 1948. Polygonaceae. In: Robyns, W., Staner, P., De Wildeman, E., Germain, R., Gilbert, G., Hauman, L., Homès, M., Lebrun, J., Louis, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 1. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 396–427.

Author(s)

• P.C.M. Jansen

PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Jansen, P.C.M., 2004. Polygonum plebeium R.Br. [Internet] Record from PROTA4U. Grubben, G.J.H. & Denton, O.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 17 December 2024.

• See the Prota4U database.