Raphionacme procumbens is one of 36 species in the genus. All but one are native to Africa.
As noted in Venter’s 2009 paper, A taxonomic revision of Raphionacme (Apocynaceae: Periplocoideae), the outlier is native to the Arabian Peninsula. Otherwise, the 35 African species are broadly distributed over the continent, with the centre of diversity in Zimbabwe and Mozambique.
Raphionacme procumbens was first described for Western science by Friedrich Richard Rudolf Schlechter in the late 1800s. The type specimen, or the specimen to which the name is formally attached, is deposited at Kew; you can see a scan of it here: Raphionacme procumbens type specimen. It is perhaps notable that the specimen contains only leaves and dried flowers. Collecting the entire plant would have been…difficult. It has a napiform, or turnip-shaped, tuber of some size (for examples, see frequent BPotD contributor Eric Hunt’s photograph or Bihrmann’s Caudiciforms page on Raphionacme procumbens). Venter notes:
Raphionacme species are utilised in various ways, and it is mostly the tuber that is collected as source of water, medicine and food, but this could also be poisonous…Few Raphionacme species are common and some, seemingly, are so rare that only a few specimens were ever collected. Some may have completely vanished from the wilds due to over utilisation during periods of drought and famine.
That said, Raphionacme procumbens is relatively common (so far assessed as a species of least concern). It occurs in Zimbabwe, Mozambique, Swaziland, and South Africa in grasslands and open woodlands. The species is characterized by hairy stems up to 40 cm long, opposite leaves, and small star-shaped deciduous flowers that are pale green in colour with purple centres. In the wild, plants flower between October and January.
Daniel adds: And in BPotD milestones, following yesterday’s twelve year anniversary of the first entry, today’s entry is number 2400.