This may be Setaria nigrirostris or black-seed bristle grass. In Afrikaans it is called swartsaadmannagras. It is a perennial grass occurring throughout the eastern summer rainfall parts of South Africa. This grass is much grazed when young, before it ripens and is perceived as a valuable veld component for livestock farming.
The species may be confused with the similar looking S. incrassata that occurs in much the same distribution area. The species is classified as a decreaser that dominates in thriving veld, but disappears in times of over-grazing and other mismanagement (Van Oudtshoorn, et al, 1991).