Geography and distribution
Pennisetum glaucum is cultivated in Eastern Europe, Africa, temperate Asia (western Asia, Arabia and China) and tropical Asia (India and Indo-China), Australia, South America, Caribbean.
Pearl millet was first domesticated in the Sahel region 4,000 to 5,000 years ago from its wild ancestor, Pennisetum violaceum. From the Sahel it spread to East Africa and southern Africa and later to the Indian subcontinent. It reached the Americas by the 18th century.
Pearl millet is cultivated as a grain crop mainly in the semi-arid regions of West Africa as well as in the driest parts of East and southern Africa and the Indian subcontinent. It is popularly grown as a fodder crop in Brazil, the US, South Africa and Australia.
Herbarium specimen of Pennisetum glaucoma
Overview: Pennisetum glaucum is an annual with erect, robust stems 150-300 cm long. The nodes along the stem are bearded and the ligule (the appendage between the sheath and the blade of the leaf) is a fringe of hairs.
Leaves: Leaf blades are 50-100 cm long and up to 70 mm wide.
Flowers: The inflorescence is a panicle (a compound of axes, known as racemes, along which the spikelets are arranged - spikelets are the clustered unit of flowers and bracts typical of grasses). Beneath each spikelet is a whorl of bristles. Spikelets are 3-6 mm long and comprise one basal sterile floret and one fertile floret. Each floret is enclosed by bracts, known as glumes, of different sizes, the lower one obscure and the upper one 0.5-2.0 mm long. The flower has three anthers and the styles are joined at the base. The flower does not contain lodicules (small structures at the base of the stamens).
Fruits: The fruit is a caryopsis (a fruit in which the seed is fused to an outer wall) 2.0-5.5 mm long which is exposed at maturity.
100 million people in parts of tropical Africa and India depend on pearl millet as their staple food source. Pearl millet can be prepared in a variety of different ways:
- The grains can be boiled or steamed directly, or ground into a flour to make bread, porridge or couscous.
- Pearl millet and pulses can be seasoned to make delicious snacks popular in Africa.
- The grain is also used in the making of alcoholic and non-alcoholic beverages. Millet beer, for example is often considered a staple of religious and social life in Africa.
- Pearl millet is high in protein which makes it an excellent feed for poultry and other livestock.
The stems of the plant are used for fencing, thatching and building materials. The red and purple varieties of pearl millet are used for making dyes for leather and wood.
Pearl millet also has a number of medicinal applications. In African traditional medicine the grain is used to treat chest disorders, leprosy, blennorrhoea and poisonings. A decoction made from the roots is used in the treatment of jaundice and the vapour from inflorescence extracts is inhaled for respiratory diseases in children.
Pearl millet has been found to be effective in suppressing root-lesion nematodes (Pratylenchus penetrans) and is being used as an alternative to soil fumigation in tobacco and potato cropping in Canada.
Pearl millet grains are used in rituals in some areas.
Crop wild relatives of pearl millet
Millets are better adapted to poor, droughty and infertile soils than most other grain crops. Even so, lower and erratic rainfall patterns are the cause of major problems and diseases, such as downy mildew, which can destroy as much as 80% of the crop. Wild relatives of pearl millet were screened for traits such as drought- and disease-resistance and were then bred with cultivated varieties that demonstrated high yield and other positive traits. An improved strain of the crop was released in 2005 by the Institute of Biological, Environmental and Rural Sciences at Aberystwyth University for cultivation throughout India and further work is being done to transfer these valuable traits into other varieties worldwide.
Pennisetum squamulatum is a relative of pearl millet that is endangered in the wild and is therefore a conservation priority. Efforts are being made by the Millennium Seed Bank and the Global Crop Diversity Trust to collect the seeds of the wild relatives of 29 of the most important food crops. The project is called 'Adapting Agriculture to Climate Change' and by protecting, collecting and preparing crop wild relatives such as Pennisetum squamulatum for use in breeding programs, their genetic potential can be harnessed to make our crops more resilient in the face 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 our seed bank vault.
Description of seeds: Average 1,000 seed weight = 7.1 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 low moisture contents without significantly reducing their viability. This means they are suitable for long-term frozen storage such as at the MSB)
Germination testing: Successful
This species at Kew
Pressed and dried specimens of pearl millet are held in Kew's Herbarium, where they are available to researchers by appointment. Details of some of these specimens can be seen online in Kew's Herbarium Catalogue.