Rhadamanthus involutus is a rare, hysteranthous-leaved species from the Bok
keveld Escarpment, west of Nieuwoudtville, Northern Cape Province, South Af
rica. Most closely related to R. albiflorus B. Nordenstam, R. involutus is
distinguished by apically recurved outer tepals that are conspicuously spot
ted with green at the base, and suberect inner tepals that have involute ma
rgins which overlap to form a tube. The bulbs grow on exposed sandstone she
ets between patches of dry fynbos and flower in midsummer.