A tall, tufted perennial grass forming large clumps, one of the most important tropical forage grasses.
Guinea grass (Panicum maximum, now Megathyrsus maximus, family Poaceae) is a large perennial bunch grass native to Africa and Yemen. It is very variable, from 0.5 to 3.5 metres tall, with open, spreading flower heads, and a single plant can bear as many as 9,000 seeds. Many of its plants set seed without fertilisation (apomixis), so their offspring are copies of the parent. It was first described in 1781 from the Lesser Antilles, where it had already been introduced, and it has since been carried throughout the tropics. Botanists moved it from Panicum to Urochloa and then, in 2003, to Megathyrsus.
In Africa it grows naturally on the more fertile soils, in open grassland and along riverbanks, often close to the trunks of thorny acacias, which give it shade and nitrogen. It needs high rainfall, at least about 1,100 to 1,300 mm a year, and fertile soil or fertiliser, and it does poorly on leached, acid tropical soils unless they are heavily limed. It withstands fire and drought, and it tolerates shade well: under about 30 per cent shade it yields more than in full sun, so it suits plantations and mixtures with fodder trees such as leucaena.
It is one of the most palatable and valuable fodder grasses of the tropics. It is cut and fed green, grazed, and made into hay and silage, and it mixes well with legumes; it is considered the most important cultivated fodder grass of tropical America and India. Its leaves contain 6 to 25 per cent protein, depending on age and nitrogen supply, but old plants become stemmy, and animals leave the thick stems of tall varieties uneaten. In the wild, buffalo, white rhinoceros and zebra graze it. In some places, such as Hawaii and southern Texas, it has become an invasive weed that crowds out native plants and raises the risk of fire.
Sources: PROTA4U database (Plant Resources of Tropical Africa), which compiles records from Royal Botanic Gardens, Kew, the Conservatoire et Jardin botaniques de Genève, FAO EcoCrop and other botanical databases; Wikipedia, "Megathyrsus maximus".
Widely grazed and cut as fodder for cattle and other livestock; a leading pasture grass across tropical Africa.
Propagated by seed or root splits; tolerates a wide range of soils and is often planted deliberately as pasture.