What is "centrostigma"

Centrostigma is a genus of flowering plants from the orchid family, Orchidaceae. There are three currently accepted species, all native to Africa:

• Centrostigma clavatum Summerh. - Tanzania, Malawi, Zambia, Congo-Kinshasa
• Centrostigma occultans (Welw. ex Rchb.f.) Schltr. - Tanzania, Malawi, Zambia, Congo-Kinshasa, Zimbabwe, Angola, Transvaal
• Centrostigma papillosum Summerh. - Zimbabwe, Angola, Malawi, Zambia