The flower by Warren McCleland, Africanplants.senckenberg.de.
This member of the
Asclepiadaceae* family was described by K. Schumann in 1893. It is
found in Angola, the Eastern and Northern Provinces of South Africa,
Swaziland, Tanzania, Zaire, Zambia, and Zimbabwe. It grows in a well
drained soil with some water and some sun. The caudex can grow up to
20 centimetres in diameter, the stem to 50 centimetres height. The
flowers are greenish purple to green.
The genera name from Greek
rhaphis; 'beet-root' and akme; 'sharpness' possibly
referring to the taste of the roots - haven't tried yet. The species
name for the spherical caudex.
*)Accordantly to the latest taxonomic system; APG IV 2016, Asclepiadaceae is now part of the Apocynaceae.