Juncus rigidus (PROTA)

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Plant Resources of Tropical Africa
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Juncus rigidus Desf.


Protologue: Fl. Atlant. 1: 312 (1798).
Family: Juncaceae
Chromosome number: 2n = 46, 48

Synonyms

  • Juncus maritimus Lam. var. arabicus Asch. & Buchenau (1882),
  • Juncus maritimus Lam. var. rigidus Desf. (1912),
  • Juncus arabicus (Asch. & Buchenau) Adamson (1935),
  • Juncus nevskii Krecz. & Gontsch. (1935).

Vernacular names

  • Sea hard rush (En).

Origin and geographic distribution

Juncus rigidus is distributed from the southern and eastern Mediterranean (including Sicily), southward to South Africa and eastward to Iran, Afghanistan and Pakistan. In tropical Africa it is distributed from Mauritania and Senegal eastward to Somalia, in DR Congo, and in all countries of southern Africa. It is not recorded from the Indian Ocean Islands.

Uses

Since the Neolithic period Juncus rigidus and other Juncus species have been used for thatching and for plaiting articles such as mats and baskets, for instance in Egypt. In ancient Egypt rush pens, most frequently made from the stems of Juncus rigidus, were used as writing implements as far back as the 3rd Century BC. In the Nile delta in Egypt small-scale cultivation of Juncus species for the production of mats was practised at the beginning of the 20th Century. In Tibesti (Niger) the stems are used for making brushes and sieves. The Tuareg in Niger are reported to eat the young shoots. Juncus rigidus is not grazed by domestic animals, except by camels, e.g. in Somalia. The seeds of Juncus rigidus and other Juncus species are employed in Asian traditional medicine as diuretic and a remedy for diarrhoea.

Production and international trade

Juncus rigidus is only used and traded locally.

Properties

Field experiments on saline soil in Egypt indicated that Juncus rigidus yields a suitable raw material for paper production, but commercial production was never realized.

Botany

Robust, perennial, glabrous herb with an up to 10 mm thick, horizontal, woody rhizome, often laxly tufted by frequent rhizome forking; stems few to many, often set in dense rows, 50–150 cm long and 2–5 mm thick. Leaves basal, reduced to a bladeless sheath or 1–5 with leaf blades; sheath open; auricles absent; blade terete, 25–110 cm long, 1.5–3 mm thick, apex pungent, sclerenchymatous. Inflorescence composed of 1 or few sessile or subsessile panicles and 1–many stalked panicles bearing a variable number of usually few-flowered heads, 5–40 cm × 2–7 cm, lax, usually elongated, usually without any secondary branches in the axils of bracteoles; heads (20–)50–150(–300); lowest two bracts leaf-like, pungent, with wide sheaths, the first 5–25 cm long, including the 2–5 cm long sheath, the second bract 2–5 cm long, including the 1.5–3 cm long sheath, upper bracts small, bracts subtending heads much shorter than flowers, ovate, amplexicaul, cuspidate, straw-coloured; heads (1–)2–4(–6)-flowered, upper part of pedicel thick. Flowers bisexual; tepals 6, elliptical-lanceolate, 2–3 mm long, equal or outer ones slightly longer, pale brown to straw-coloured or when young greenish in centre, with broad, translucent, membranous margins, outer tepals narrowly ovate, boat-shaped, acute to obtuse, inner tepals oblong, obtuse; stamens 6, anthers 1–2.5 mm long, 3–6 times as long as filaments, yellow when young; ovary superior, 3-celled, style c. 1 mm long, stigmas 3, 1–1.5 mm long. Fruit a narrowly trigono-ovoid capsule 3.5–5 mm long, mostly conspicuously exceeding the tepals, apex tapering, trigonous, sometimes abruptly contracted, mucronate, usually pale brown to straw-coloured, 3-celled, 70–90-seeded. Seeds obliquely lanceolate, 1–2 mm long, 20–25-striate, reddish-brown, with prominent, pale, basal and apical appendages. Seedling with epigeal germination; first leaves very small, more or less U-shaped in cross section, 3rd and later leaves usually similar to adult ones.

Flowering is protogynous. Flowering starts early, well before the plant has reached its full adult height, which is usually reached after a few years. Early inflorescences are usually small.

The genus Juncus comprises 200–300 species of grass-like plants called rushes. They occur in wetlands all over the world, but are rarer in the tropics than more temperate regions. Juncus is divided into several subgenera; subgenus Juncus comprises 9 species occurring throughout the world. The species mentioned here are all classified in subgenus Juncus.

Juncus rigidus has often been confused with Juncus maritimus Lam., a related species with a more temperate distribution. It can be distinguished by its more obtuse capsule only slightly longer than the tepals.

Juncus acutus L. (‘sharp rush’) is a perennial, densely tufted rush with an extremely abbreviated, inconspicuous rhizome. It is distributed mainly in subtropical and warm temperate areas of Pacific and Atlantic Latin America and California, the islands of the Atlantic Ocean, including Cape Verde, North and South Africa and oceanic and southern Europe extending to Afghanistan and Pakistan, and in Australia and New Zealand. The stems are used for thatching and for making woven articles such as baskets and mats.

Juncus kraussii Hochst. is a perennial rush with a creeping, usually short-noded and densely branched rhizome, usually densely mat-forming. It is distributed in southern Africa, South America and Australia and is divided into 3 regionally separated subspecies. Subsp. kraussii (‘salt-marsh rush’) occurs in coastal South Africa, southern Mozambique and Madagascar, in both salt and fresh-water marshes, on river margins, rarely in maritime sand. Its stems are a favourite material in KwaZulu-Natal for making sleeping mats, including traditional bridal mats. They are also used for making water-tight baskets and household appliances. The species is locally heavily exploited, but in some places harvesting is well controlled through permits and the plant also grows in protected areas. It can be cultivated, also in freshwater rice fields.

Ecology

Juncus rigidus typically occurs in maritime and inland, usually sandy, saline localities, from near sea-level up to 900 m altitude and up to nearly 2000 m in Katanga (DR Congo). It is found in Saharan oases, coastal sand-dunes, wadis, springs, depressions and other permanently or seasonally wet places in desert and steppe areas. In the Mediterranean part of its distribution it occurs in maritime localities, in Africa in inland localities. In coastal South Africa it is replaced by Juncus kraussii.

Management

The seeds of Juncus species require constant moisture for at least several weeks to germinate. They germinate best when placed on the soil surface and in the light. When covered with a layer of sand or soil most seeds do not germinate. Seeds of Juncus rigidus germinate under saline conditions; in tests with a salt concentration of 3%, 80% of the seeds still germinated if the temperature was 10–20°C, while at 20–35°C, the same salt concentration totally inhibited germination. The germination rate of seeds harvested the same or the previous year is usually 95–100%. In a salt marsh in Egypt, the estimated net annual primary production was 21.5 t/ha.

Genetic resources

Juncus rigidus is widespread and locally common and is not in danger of genetic erosion, but as a component of wetlands and oases in the Sahara desert it needs protection.

Prospects

Juncus rigidus and other rush species are important sources of material for weaving and wickerwork and will remain an important resource for traditional handicrafts. Cultivation is easy and could be pursued to ascertain supplies. The role Juncus rigidus could play in the reclamation of saline land and in constructed wetlands for clearing polluted water deserves research attention.

Major references

  • Burkill, H.M., 1995. The useful plants of West Tropical Africa. 2nd Edition. Volume 3, Families J–L. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 857 pp.
  • Hepper, F.N., 1972. Juncaceae. In: Hepper, F.N. (Editor). Flora of West Tropical Africa. Volume 3. 2nd Edition. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 277–278.
  • Lye, K.A., 1995. Juncaceae. In: Thulin, M. (Editor). Flora of Somalia. Volume 4. Angiospermae (Hydrocharitaceae-Pandanaceae). Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 95–98.
  • Mansfeld, R., 1986. Verzeichnis landwirtschaftlicher und gärtnerischer Kulturpflanzen (ohne Zierpflanzen). 2nd edition, revised by J. Schultze-Motel. 4 volumes. Springer Verlag, Berlin, Germany. 1998 pp.
  • Snogerup, S., 1993. A revision of Juncus subgen. Juncus (Juncaceae). Willdenowia 23(1/2): 23–73.

Other references

  • Alshammary, S.F., 2007. Some potential plants of coastal and inland salt affected soils and their relation to soil properties. Asian Journal of Plant Sciences 6(5): 821–826.
  • Lisowski, S., Malaisse, F. & Symoens, J.J., 1973. Juncaceae. In: Bamps, P. (Editor). Flore d’Afrique centrale. Spermatophytes. Jardin botanique national de Belgique, Brussels, Belgium. 13 pp.
  • Lymbery, A.J., Doupé, R.G., Bennett, T. & Starcevich, M.R., 2006. Efficacy of a subsurface-flow wetland using the estuarine sedge Juncus kraussii to treat effluent from inland saline aquaculture. Aquacultural Engineering 34(1): 1–7.
  • Naidoo, G. & Kift, J., 2006. Responses of the saltmarsh rush Juncus kraussii to salinity and waterlogging. Aquatic Botany 84(3): 217–225.
  • Obermeyer, A.A., 1985. Juncaceae. In: Leistner, O.A. (Editor). Flora of southern Africa. Volume 4, part 2. Botanical Research Institute, Department of Agriculture and Water Supply, Pretoria, South Africa. pp. 71–91.
  • Perrier de la Bâthie, H., 1946. Juncacées (Juncaceae). Flore de Madagascar et des Comores (plantes vasculaires), familles 38–39. Imprimerie Officielle, Tananarive, Madagascar. 5 pp.
  • Sadek, L.A., 1996. Annual aboveground primary production and mineral dynamics of Juncus rigidus in a salt marsh of the Mediterranean coastal region of Egypt. Desert Institute Bulletin 46(1): 127–151.
  • Traynor, C.H., 2008. Juncus kraussii harvesting in Umlalazi Nature Reserve, KwaZulu-Natal, South Africa: socio-economic aspects and sustainability. African Journal of Aquatic Science 33(1): 27–36.
  • Traynor, C.H., Kotze, D.C. & Mckean, S.G., 2010. Wetland craft plants in KwaZulu-Natal: an ecological review of harvesting impacts and implications for sustainable utilization. Bothalia 40(1): 135–144.
  • van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.
  • Zehran, M.A., 1979. The halophytes and their economic potentialities. Proceedings of the Saudi Biological Society 3: 133–137.

Author(s)

  • L.P.A. Oyen, PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Oyen, L.P.A., 2011. Juncus rigidus Desf. [Internet] Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 6 March 2020.