A thank you to sandy130 @ UBC Botanical Garden Forums from Abbotsford, BC for sharing today's image of the (inaptly-named) toad cactus or star cactus (it's not a cactus!). A better common name in use is African carrion flower. Check out the discussion thread to see a second photograph and the ensuing discussion. Much appreciated, sandy130!
Formerly placed in the genus Stapelia (an example), Orbea was resegregated as its own genus by Leach in this paper: Leach, LC. 1978. A contribution towards a new classification of Stapelieae (Asclepiadaceae) with a preliminary review of Orbea Haw., and descriptions of three new genera. Excelsa Taxonomic Series, No. 1. Aloe, Cactus and Succulent Society, Rhodesia.
Stoffel Petrus Bester of the South Africa National Herbarium has written an excellent summary of the genus Orbea, so I'll kindly ask you visit that site for more information about Orbea variegata and its relatives.
I'll also add that this species is an exotic invasive in South Australia. See: Dunbar, KR and Facelli, JM. 1999. The impact of a novel invasive species, Orbea variegata (African carrion flower), on the chenopod shrublands of South Australia. Journal of Arid Environments. 41(1): 37-48.
Photography resource link: for inspiration, the alpine photography of Jack Brauer. Locales photographed include Turkey and Patagonia.