Oryza glaberrima (African rice)
Detail of a herbarium specimen of Oryza glaberrima
Oryza glaberrima Steud.
Widespread in cultivation.
African rice grows best on fertile alluvial soils although it tolerates low soil fertility and can produce higher yields than Asian rice on alkaline and phosphorus-deficient soils. Floating rice is planted on loam or clay soils.
Food, medicine, livestock feed, ritual.
About this species
There are only two species of cultivated rice in the world: Asian rice (Oryza sativa) and African rice (Oryza glaberrima). African rice is native to West Africa, where it is cultivated as a foodcrop. It is known for its hardiness and its ability to compete with weeds, pests, infertile soils and human neglect. However, increasingly African rice is being replaced by the introduced Asian varieties of Oryza sativa, which produce a higher yield than African rice, shatter less easily and have a softer grain that is easier to mill.
African rice is still an important crop for small-scale farmers who grow it for its nutty flavour and other culinary qualities. It is also used in a ritualistic context and as a treatment in African traditional medicine.
Geography and distribution
Oryza glaberrima is native to West Africa and grows in the region extending from the delta of the River Senegal to Lake Chad in the east. The most intensive areas of cultivation of African rice are the floodplains of northern Nigeria, the inland delta of the Niger River, parts of Sierra Leone and Ghana.
African rice was introduced to the New World during the days of the slave trade and today is cultivated in parts of Brazil, Guyana, El Salvador and Panama. Oryza glaberrima is thought to have been domesticated from its wild ancestor Oryza barthii around 1,500 BC in the inland delta of the Niger River. Today Oryza barthii can be found growing wild in parts of Africa.
Overveiw: Oryza glaberrima is an annual with erect stems up to 90-150 cm long. The sheaths which enclose the stems are smooth and hairless.
Leaves: The leaf blades are 20-30 cm long and 10-15 mm wide and pointed at the tip.
Flowers: The inflorescence is a panicle (an extensively branched inflorescence) 15-25 cm long. The spikelets (clustered units of flowers and bracts) are solitary. The fertile spikelets comprise two sterile florets at the base and one fertile floret. The spikelets are about 8 mm long and remain on the plant when mature. The glumes (empty bracts that enclose the florets) are absent or obscure. The flower contains two lance-shaped (lanceolate) lodicules (small structures at the base of the stamens). Each flower has six anthers and two stigmas.
Fruits: The fruit is a caryopsis (a dry fruit where the fruit wall is attached to the seed).
African rice is a staple food which can be prepared in similar ways to Asian rice (Oryza sativa). Broken grains are used to feed chicken and other livestock. Some cultures in West Africa, such as the Jola of southern Senegal grow African rice to be used in traditional ceremonies and rituals.
African rice also has many medicinal benefits: for example, in the Central African Republic the root is eaten raw as a remedy for diarrhoea.
Crop wild relatives of African rice
The Millennium Seed Bank and the Global Crop Diversity Trust are engaged in a ten-year project, called 'Adapting Agriculture to Climate Change'. The project aims to protect, collect and prepare the wild relatives of 29 key food crops, including African rice, so that they are available to pre-breeders for the development of new varieties that are more resilient to the effects of climate change.
Millennium Seed Bank: Seed storage
The Millennium Seed Bank Partnership aims to save plants worldwide, focusing on those plants which are under threat and those which are of most use in the future. Once seeds have been collected they are dried, packaged and stored at -20°C in Kew’s Millennium Seed Bank vault.
Description of seeds: Average weight of 1,000 seeds = 26.5 g
Number of seed collections stored in the Millennium Seed Bank: One
Seed storage behaviour: Orthodox (the seeds of this plant can be dried to a low moisture content without significantly reducing their viability which means they are suitable for long-term frozen storage)
Germination testing: Successful
This species at Kew
Pressed and dried specimens of African rice are held in Kew's Herbarium, where they are available to researchers by appointment. Details and images of some of these specimens can be seen online in Kew's Herbarium Catalogue.
Beentje, H. (2010). The Kew Plant Glossary: an Illustrated Dictionary of Plant Terms. Royal Botanic Gardens, Kew.
Brink, M. & Belay, G. (2006). Cereals and Pulses: Volume 1 of Plant Resources of Tropical Africa. PROTA.
Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. Available online (accessed 21 August 2013).
Linares, O.F. (2002) African rice (Oryza glaberrima): History and future potential. PNAS 99: 16360-16365
Mabberley, D.J. (2008). Mabberley’s Plant-book: a Portable Dictionary of Plants, their Classification and Uses. Third edition. Cambridge University Press, Cambridge.
Royal Botanic Gardens, Kew (2008). Seed Information Database (SID). Version 7.1. Available online (accessed 21 August 2013).
Kew Science Editor: Sarah Cody
Kew contributors: Maria Vorontsova
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