This plant is native to Natal, Cape Province, and Angola. It has been Known Since 1905.
This is one of the easiest of all the ceropegias to grow, with only woodii and the debilis varieties being easier. It has medium thick stems, fibrous roots, and its leaves are not succulent. It will root where it touches the ground. I would suggest that you start new plants at least every two years if not every year. The previous years stems turn white and after a few years they seem less capable of supporting new growth. New roots in new soil will grow a more rewarding plant.
Haygarthii blooms profusely for a long period during the summer; I suspect in warmer climates, with annual re-potting and heavy feeding it could be in continuous bloom. Temperature seems to be the sensitive issue. I've had buds appear in early April as the days begin to noticibly lengthen, however, they would all abort until temperatures at night were above 60° F.
September 2002 - Here are some new shots of the inside of the flower. I was surprised by the amount of color inside especially the sharp border of graded color to spotted and striped area.
The interior tips where the corolla is joined is delicately shaded. And you can see the varys in hairyness from the opening down to the stigma area. The picture also shows that the antenna pole is twisted, nature's way of strengthening a delicate structure.
To the left is a picture of the just opening 'antenna'. You can see how the 'hairs' are attached only to the margins of the opening flaps, they were folded inside while the flower was a bud.
Here is a close-up of the corolla extentions and pollonaria part of the flower. This particular bloom had four-sided instead of the usual five-sided symmetry. The four-sided symmetry was carried out from the antenna to the structure in the base of the tube.