AFRICAN

ORCHIDS

Centrostigma Schltr. in Bot. Jahrb. Syst. 53: 522 (1915).
Description:
Plants terrestrial, perennating with tuberous roots; stems leafy; leaves linear-Ianceolate, imbricate, grading apically into the floral bracts. Inflorescences terminal, to 20-flowered; bracts leafy, green, about as long as the pedicels plus ovaries. Flowers resupinate, medium to large, white, cream-coloured or green. Sepals unequal; median galeate; lateral s obliquely spreading. Petals like the lateral sepals but smaller. Lip united with the gynostemium at the base, deeply 3-lobed; side lobes in our species fringed; spur cylindrical. Gynostemium erect, short; anther curved; pollini sectile, with the caudicles and viscidia separate; stigma developed into distinct processes, each one bilobed above the base, with the lower lobe receptive and the upper sterile; rostellum 3-1obed, central lobe small, lateral lobes upcurved.
Type species: Centrostigma occultans (Welw. ex Rchb.f.) Schltr.
Distribution:
Tanzania to S. Africa
Notes:
On account of a very similar structure also this genus was in the past included in Habenaria, but differs in the longitudinal division of the stigmatic processes. It may well be a specialized group within Habenaria which merits sectional rank rather than that of a separate genus (Kurzweil & ] Weber 1992). However, in the absence of a careful, comparative treatment of Habenaria, it is here retained as a separate genus.
Cultivation:
Not in cultivation
Species:

Centrostigma clavatum Summerh. Tanzania to Zambia.
Centrostigma occultans (Welw. ex Rchb.f.) Schltr. Tanzania to Angola and Northern Prov.
Centrostigma papillosum Summerh. S. Trop. Africa.

World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/ accessed 1/16/2010
Bibliography and References:

Kurzweil H, Weber A. 1992 Floral morphology of southern African Orchideae: II. Habenariinae. Nordic J. Bot. 12. 39-61. Bonatea, Cynorkis, Habenaria, Platycoryne, Stenoglottis, Centrostigma, Roeperocharis. Gynostemium development.