Floral morphology of southern African Orchideae. II. Habenariinae

The floral morphology of the southern African genera of Orchideae‐Habenariinae (Bonatea, Cynorkis, Habenaria, Platycoryne, Stenoglottis, Centrostigma and Roe‐perocharis) is surveyed paying special attention to the gynostemium. Ontogenetic data are provided for the species from which adequate material was available. It is shown that the floral architecture is essentially an elaboration and complication of that found in the better known Orchidinae. The structural similarities are particularly evident in the early ontogeny. Although the tribe Orchideae is commonly said to have gynostemia with erect anthers, a few Habenariinae are reported here to have reflexed anthers. In most cases both ‘auricles’ (filament excrescences) and ‘basal bulges’ (staminodes) are united to form the lateral gynostemium appendages. The primordia of both structures are clearly recognizable in the early ontogeny in all species studied. In Habenaria dregeana the basal bulges are only basally fused to the auricles, but in their main portion become adnate to the lip and petal bases: the auricles then solely form the lateral gynostemium appendages. It is suspected that this occurs also in other species not studied here. Systematic and phylogenetic aspects of the southern African representatives of the Habenariinae are discussed: the generic separation of Bonatea, Platycoryne and Centrostigma from Habenaria does not appear justified. Cynorkis, Roeperocharis and Stenoglottis are morphologically dissimilar to Habenaria. Based on the findings in the southern African taxa the status of the Habenariinae, Orchidinae, Orchideae and Diseae is discussed: there is no clear distinction between Habenariinae and Orchidinae; while the Diseae seem to represent a monophyletic group, the Orchideae are possibly polyphyletic.