Saw this in the veld near Bela-Bela next to a dirt road. Harvested a small piece and rooted it in some of the sandy soil from the original site. Couldn't ID the Huernia subspecies. But then a small flower bud came up from just beneath the soil. Took a couple of weeks before it opened. Could then identify as a Transvaalensis (very similar to the Zebrina, but with more irregular markings).
The cutting took easily in the moist soil. Changed colour to a brighter over the few weeks from late Dec to early January - probably because it got less sun than in original spot (rocky outcrop).
Flower had no smell that I could detect. Saw no insects visiting.