Taxonomic Study of Grasses (Poaceae) in the Fadama Wetlands of Kebbi State

Fadama wetland grasses in Kebbi State, North West Nigeria, constitute important components of pastoral and agricultural landscapes, yet their taxonomic diversity and ecological significance have not been systematically studied. This study conducted a taxonomic survey of Poaceae species in the fadama wetlands of three Local Government Areas in Kebbi State: Birnin Kebbi, Yauri, and Argungu. Vegetation surveys were conducted along 500m transects within the wetland and wetland-upland transition zones during the wet and dry seasons. Grass specimens were collected, pressed, and identified using the Flora of West Tropical Africa and other standard references, with verification at Usmanu Danfodiyo University Herbarium. A total of 52 grass species from 36 genera were identified. Andropogoneae was the most represented tribe (14 species), followed by Paniceae (11 species) and Chlorideae (9 species). Seasonal flooding influenced species composition, with Oryza barthii, Echinochloa pyramidalis, and Vossia cuspidata characteristic of flooded zones. Upland-wetland transition zones had the highest species richness (38 species). Economically important fodder grasses including Brachiaria mutica and Pennisetum purpureum were common in the transition zone. Invasive Echinochloa colona dominated degraded fadama margins. A dichotomous identification key was constructed for the 52 recorded species. The study provides the first comprehensive taxonomic treatment of fadama wetland grasses in Kebbi State and recommends this reference for future ecological and range management studies in the North West zone.

Keywords: Poaceae, fadama wetland, grass taxonomy, Kebbi State, pastoral ecology