Haworthia janvlokii (Breuer) is an attractive and interesting retusoid Haworthia that grows near the Kammanassie Dam in between Oudtshoorn and De Rust. The plants share similarities with Haworthia picta as well as Haworthia comptoniana.
The geographic distribution of this species is closer to Haworthia picta than Haworthia comptoniana which occurs in the Willowmore district. The plants have a characteristic dull smooth epidermis and are found amongst ferri-crete and quartz pebbles on both the southern and northern slope of a mountain. Although here and there some characteristics of Haworthia comptoniana may be seen the plants are morphologically closer to Haworthia picta.
Also following contribution received by Gerhard Marx:
Haworthia picta var janvlokii was discovered by Jan Vlok in 1989 during a botanical survey of the area east of the Kammanasie Dam. This variety of H. picta does show several features that make it a transitional form between H. comptoniana and other H. picta elements occuring to the west. It has the same smooth and somewhat glossy upper leaf surface and can also grow to a slightly larger size than the average H. picta. It lacks the dark green colour of H. comptoniana and varies from blue-green to yellow-brown, depending on exposure. The lines on the leaves are separate and parallel and not connected in reticulated patterns like in H. comptoniana. The white flecks in between these lines are very fine and more numerous than in H. comptoniana. The leaves are also slightly narrower and longer than those of H. comptoniana. The few small closely adjacent populations are all on the upper northern slope of the Paardeberg hills. Despite growing on the sun-facing northern slope, the plants are mostly hidden in dappled shade below Pteronia and other shrubs. The surrounding pebbles are quartzite conglomerate and the altitude is about 650 metres. A form of Haworthia scabra grows here alongside H. picta var janvlokii. Euphorbia enopla is also locally plentiful as well as Cotyledon orbiculata. Haworthia mucronata var. morrissiae grows lower down on the same slopes and H. arachnoidea var. aranea is also nearby and is found on the southern slopes of the higher Paardeberg hills. Towards the eastern edge of the Paardeberg occurs the interesting summer flowering H. bayeri-related element that was published as Haworthia jadea (Hayashi).