I'm interested in finding out what species/types of grasses and/or reeds are used for roof thatching in Southern Africa?

The roofs of chalets and similar huts in Zimbabwe were very neat and effective. Much better than any I have ever seen here in Australia or in SE Asia. Very thick, waterproof and nice and cool in hot weather.

The grasses used appeared to be almost reed-like with hollow stems.

Looking to identify the grass or reed species used and if known their characterisitics. Thanks