Any plant growing where it is not wanted is a weed. A plant may occupy an important ecological niche in the wild; it may possess aesthetically pleasing characteristics. It may serve mankind with its medicinal properties. But if it grows in a West African cultivated field and competes with a cash crop for nutrients, moisture and light, the farmer will call it a weed.
Imperata cylindrica, also called cogon grass or speargrass, is an attractive plant which serves as a folk remedy for diarrhea in the Philippines. But in such West African countries as Cote d’Ivoire, Nigeria and Benin, it is a troublesome weed that hampers agricultural production, according to Science Direct.
Some West African farmers use Chromolaena odorata, a plant of the pea family, to cover lands that are temporarily lying fallow. Later, when the farmer sows a cash crop on this land, Chromolaena odorata often propagates itself and becomes a weed. In spite of this, Chromolaena odorata does more good than harm since it prevents the more troublesome speargrass from establishing itself on the land while it is lying fallow, according to Social Partnerships in Learning.
Cyperus rotundus, popularly called nutgrass, may look like a grass, but it is actually a sedge. It occurs not only in the tropics, but also in such cooler countries as the United States and southern Australia. Sedges are interesting plants with triangular stems. West African farmers regard Cyperus rotundus as an annoying weed, according to Science Direct.
Euphorbia heterophylla, called the Mexican fire plant in the United States and milkweed in Australia, grows only in tropical or subtropical climates. It shares the same genus with Euphorbia esula, the leafy spurge, an especially noxious weed in the United States. Euphorbia heterophylla likewise causes problems for farmers, including those of West Africa, according to Science Direct.
Tridax procumbens has different names in different West African languages. In the Chamba dialect it bears the title nuke-noh, which indicates that the Chambas believe that the plant grew from grasshopper dung. Nuke-noh is a medicinal plant that might prove helpful to diabetics, according to the International Journal of Green Pharmacy; however, West African farmers regard it as a weed, according to Science Direct.
An especially noxious West African weed is witchweed, a name applied to some species of the genus Striga. Witchweed, a parasitic plant, penetrates the root systems of other plants, usually grasses and cereal grains, and robs the host plant of its nutrients, according to the International Development Research Centre archive.
Species of Digitaria
Digitaria abyssinica, variously called finger grass or couch grass, causes problems in Nigeria, according to the USDA. Other species of Digitaria also grow in West Africa.
West Africans like to eat the leaves of Commelina benghalensis, the dayflower, but farmers do not like it when it invades their fields, according to Protabase.
Hyptis spicigera, the American bushmint, belongs to the mint family. Though it grows as a weed in West Africa, it is not a serious pest. In fact, its oil is an insecticide with a potential to control agricultural pests.