Gramineae
O. barthii auctt., non A. Chev.
Wild rice, red rice, long-stamen rice
Bambusoideae; Oryzodae, Oryzeae
There are 25 species of Oryza from tropical regions of the world of which 3 species are indigenous to southern Africa. Oryza longistaminata occurs throughout tropical Africa and Madagascar. This includes the following countries: Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Central Africa Republic, Chad, Congo, Côte d'Ivoire, Democratic Republic of Congo, Ethiopia, Gabon, The Gambia, Ghana, Kenya, Madagascar, Malawi, Mali, Martinique, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Seychelles, Sierra Leone, Somalia, South Africa, Sudan, Tanzania, Uganda, Zambia, and Zimbabwe.
An erect, perennial hydrophytic grass with extensive, branched rhizomes that grows to a height of 2,000 mm tall or more. Culms are spongy. The leaf blades are auriculate, 450 mm long and 15 mm wide. The ligule is an unfringed membrane, 15-45 mm long and acute or 2-cleft, > 15 mm. The inflorescence is an open or loosely contracted panicle. The spikelets are 4.5-11.5 mm long, compressed laterally and disarticulating above the glumes. Spikelet-bearing axes persistent. Lemmas are 3-9 nerved, entire, with awns 40-80 mm long. Palea present that is relatively long but narrower than the lemma. The anthers are 1.5-8.2 mm long.
Ecologically important in swamps and floodplains.
Chromosome base number, x = 12. 2n=2x=24.
C3 photosynthetic pathway.
None reported and considered to be non-toxic.
Found in swampy areas,
at the edges of lakes or ponds, streams or river sides, in irrigation
canals, in and at the edges of rice fields. Grows in water up to 4 m deep,
but usually 1 m or less, in open savanna or openings in rain or gallery
forests. Grows in full sunlight.
Found in the inland delta of the Niger.
In South Africa O. longistaminata is found on the floodplains
of Nylsvly wetland system, where it is a keystone species in the ecology
of the wetland system. Dominance by this species is checked by the disturbance
of warthogs that forage on the floodplain during the dry season and create
patches where other species have an opportunity to become established.
O. longistaminata at Nylsvly only spreads vegetatively and it is
thought that the entire population is a single genetic clone, effectively
a single individual. This makes it extremely vulnerable to disturbance
since it does not have the genetic variability at this site to accommodate
environmental shifts. This characteristic may be present throughout the
whole geographic range of the species but no research has been undertaken
to investigate this.
Prefers black cotton soils, Kalahari sand, and alluvium. Found in waterlogged or seasonally inundated silty soils in wetlands and floodplains.
Unknown
Summer growing species that flowers from October to May. In certain parts of its distribution range such as in South Africa the seeds of this species are not viable and it only spreads vegetatively.
None known
Performance
Moderate to slow -growing.
Gibbs-Russell, G.E., Watson, L., Koekemoer, M., Smook, L. Barker, N.P., Anderson, H.M., Dallwitz, M.J. 1989. Grasses of southern Africa. Memoirs of the Botanical Survey of South Africa, No. 58, National Botanical Institute, Pretoria.
Gibbs-Russell, G.E., 1986. Significance of different centres of diversity in subfamilies of Poaceae in southern Africa. In: E.M.Van Zinderen Bakker, J.A.Coetzee & L.Scott (eds.) Palaeoecology of Africa and the surrounding islands. Vol. 17. pp. 183-191. A.A.Balkema, Rotterdam.