Grewia robusta, the Karoo cross-berry, is a hardy shrub or small tree similar to G. occidentalis, the cross-berry or kruisbessie in Afrikaans. Their distributions overlap, but the Karoo cross-berry has a much more restricted habitat in the southern and Eastern Cape, whilst G. occidentalis is found from the Cape to Zimbabwe along the eastern parts of the country.

G. robusta has much smaller leaves, grows in a more compact fashion and flowers more profusely (in summer). Like Karoo plants it is drought tolerant (Coates Palgrave, 2002).