A slow-blooming colour splash brightens every north-facing hillside in the Eastern Cape Karoo each winter, with colonies of ferocious thorn-lined leaves upright and motionless against the icy winds.

In the winter of 2004, a slightly-built guy with bushy eyebrows and a studious mien arrives out of a dust storm in a middle-of-nowhere place called Rietbron. Pedestrians don’t pitch up at Rietbron ...