Streptocarpus haygarthii is a monocarpic unifoliate (leaves sometimes 400 x 350 mm), which means that it dies after flowering/fruiting and has only a single leaf. There is significant size, shape and colour variation in its keyhole shaped flower, ranging from 8 mm long with very short corolla lobes in the south of its range, in the Bulolo Gorge near Port Saint Johns in Pondoland (Eastern Cape Province, South Africa) to much larger, 45 mm corollas with longer corolla lobes that can either have larger rounded or much narrower lobes, to the north of its range into the Drakensberg (inland KwaZulu Natal Province, South Africa). Hilliard and Burtt (1971) recognized different sizes and lobe forms of the corolla over its range which show that this is probably a species complex rather than a single species.

What is distinctive is that corolla shape and size does not vary within populations but there are major differences in flower shape and size between populations. Much more field work accompanied by laboratory DNA analysis will be required to unravel the complex relationships of the different forms of this species.

Single-leaf species, like S. haygarthii, often grow on vertical surfaces with the leaf hanging straight down. The unifoliate form is particularly well-adapted to such a position, as a taller plant with leaves sticking out would tend to pull out of the very shallow medium (mainly moss) within which the plant is rooted. Colonies can efficiently cover almost the entire surface of such a rock or tree.

• A close view of the elegant flowers on the feature plant above
• The beautiful flowers on a different plant
• The flower shape and color of different populations of the species can vary substantially
• Flower size can also vary substantially
• Some populations of S. haygarthii have very long flower stalks
• The single leaf can be very large
• A colony on a vertical rock face, with the pendant leaves covering almost all of the available surface