E. A. Bruce had this taxon under observation for several years after 1948 but came to no definite decision on its classification. To make it a subspecies of her C. decidua seems the best solution. Like subsp. decidua, subsp. pretoriensis is not infrequently found in association with C. rendallii. The difference in the shape of the inner corona-lobes which are spathulate-acuminate and tapering to base in C. decidua and broadly falcate in C. rendallii, with no aparent intermediates, throws doubt on the possible influence of hybridization with C. rendallii.