Hoodia gordonii is a leafless spiny succulent plant with medicinal uses. It grows naturally in South Africa and Namibia. The flowers smell like rotten meat and are pollinated mainly by flies. The indigenous Bushmen call this plant ǁhoba (pronounced [ǁʰɔbɑ]; the initial sound is a lateral click). ... (Heh! ... you DO know how to do a lateral click hey?)
The use of Hoodia spp. has long been known by the indigenous populations of Southern Africa, who infrequently use these plants for treating indigestion and small infections. However, it is their centuries old use of the meat of the plant to suppress appetite when making long hunting trips in the Kalahari Desert that has stimulated the most interest.
There is no published scientific evidence that hoodia works as an appetite suppressant in humans.
As Hoodia gordonii is a species threatened with extinction if international trade is not monitored, it is listed under CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) and is illegal to export from Africa without a CITES certificate being issued by proper authorities.
I believe that Oprah Winfrey was/is promoting Hoodia as a wonder weight-loss drug - I haven't seen any recent images of her so I don't know if it works ...
... I took these pics three or four years ago after an unusually good rain-season which caused the desert to burst into flower.