The African rye or wilderog (Secale africanum) is only known from the southern African escarpment margin between Sutherland and Middelpos in the Northern Cape, at altitudes of between 1 400-1 900 m, in an area known as the Roggeveld. Its habitat is the Roggeveld Shale Renosterveld (FRS3) (Mucina et al 2006). In fact, the name Roggeveld means ‘rye field’, and pertains to the region where this wild African rye grows. The name is misleading as, according to Burchell (1, 256), he did not see any of this grass whilst traveling through the Roggeveld. He responded to Thunberg’s claim that the wild rye grows in abundance among the bushes (Thunberg ed. 3 2, 268). However, this is a perennial grass but it does not grow scattered among the local Renosterveld vegetation but is confined to moist meadows and streambanks. It is probably here where Thunberg observed his plants. Here it does grow commonly, especially after good winter rainfall. This perennial grass can be found in in seasonally moist meadows and riverbanks and other depression on the Roggeveld. It grows in rich loam to loamy-clay soil and the plants seem to remain in this habitat. The region is hilly with broad valleys dominated by the renosterbos (Dicerothamnus rhinocerotis) and is very rocky in part. The geology consists of Beaufort mudstones of the Karoo Supergroup, with dolerite intrusions. At Kanariesfontein on the farm of Koos Esterhuysen, plants were observed in deep alluvium soils adjacent to a stream bed, growing with other grasses and perennials such as Ehrharta calycina, Anchusa capensis, Chrysocoma oblongifolia, Dimorphotheca cuneata and Eriocephalus africanus.

Fig. 5. The African rye (Secale africanum) in its meadow habitat on the farm Kanariesfontein, note the Renosterveld vegetation in the background.

The climate, compared to other parts of South Africa, is harsh, especially in winter with a high frost incidence of up to 70 days per annum. The mean annual rainfall is about 300 mm per annum, and falls as a result of both convectional rain during spring or autumn and cyclonic cold fronts from the south during winter. The area is also subject to droughts. Summers are hot but with cooler nights.