A reed-like rhizomatous perennial grass, culms robust, erect to 3½ m high, or creeping or floating to 4½ m long; of river-banks, marshes, open water and riverine meadows; common across the whole Region from Senegal to W Cameroons, and widespread in the rest of tropical Africa and into S Africa and Madagascar.The grass forms great prairies in the flood plains of rivers, especially along the Senegal and Niger Rivers, and in the inundation area of Lake Chad. It thrives in permanent water and withstands seasonal flooding. It is a major constituent of sudd in the Niger and Nile Rivers, and is invading some parts of the Volta Lake (11). It is a weed of cultivation. Fula of N Nigeria say that it is a particularly bad weed of sorghum fields, but consider its presence is indicative of soil fertility (28). It is an invader of irrigation (rice-fields — The Gambia: 18, 26; Nigeria: 12; sugar — Nigeria: 14, 15). By its robust habit and deep-penetrating roots it creates a good protection on river-banks against scour and erosion (27). It readily tillers rooting at the nodes even high up the culms, thus propagation from such offshoots is readily established (22).It is an excellent fodder for all stock (7; Senegal: 1–3, 17; Upper Volta: 13; Ghana: 11; W Cameroons: 20; Kordofan: 6; Sudan: 8; Kenya: 10, 19). The stems tend to be juicy, which makes them the more palatable whilst still green. It makes a good hay, for which in Senegal it is cut twice annually (1). It is reputed to be a particularly good fodder for horses (1, 13, 20), but Hausa believe it makes horses fat, not strong (7). If allowed to grow without cutting, the culms may well become too tall for browsing by any stock.The culms are used in Kordofan to make enclosures (6), and there (6), as in E Africa (10), they are used as thatch. In places the haulm is incinerated to produce a vegetable salt consisting mainly of sodium carbonate (Senegal: 1; Nupe, Nigeria: 4, 5, 7). This is used as a substitute for normal salt.The root is said to have a pleasant smell and a decoction is drunk in the Central African Republic as a deodorant (9). Nueyr in Sudan chew the root for cough (24). Flavones and glycosides have been detected in Zaïrean material (25).The grass is one of a group occurring in the Sahel, the grain of which is edible and is collected under a general term ‘kreb’ for human consumption on a regular basis in the Niger and Nile valleys (21), and more especially in time of shortage (1, 4, 7, 12, 16), cf. Panicum turgidum, Gramineae. The grain is normally ground to flour. In Sudan the seed is reported eaten as a sort of condiment ‘like sugar’ (23).