The fruits of the Karoo cross-berry do not here show the fully developed four-lobed square cross structure of seed positioning very clearly. One cluster has a fourth seed that is somewhat underdeveloped, while the others are incomplete as often happens in the challenging conditions presented by the habitat. The reddish brown fruit colour is typical. The photo was taken near Beaufort West in the Karoo in May, about halfway through the normal fruiting season.

The small, alternate leaves are slightly asymmetric and elliptic to ovate in shape. The leaf margins are toothed or scalloped. Leaf colour, yellowish green here, may be darker on top while pale on the lower surface where short hairs would be present. There is pale grey bark on the rigid, twiggy branches.

Both fruit and leaves of Grewia robusta are browsed by game and stock (Coates Palgrave, 2002; Shearing and van Heerden, 2008).