Developmental studies in orchid flowers II: Orchidoid species

The floral development of 11 species of Orchidoideae (sensu Rasmussen 1985) was studied by means of SEM, paying special attention to the early development of the gynostemium and its appendages. In contrast to the staminodes found in epidendroid and vandoid orchids, the 'auricles' of the tribe Orchideae are developed on the dorsal side of the fertile anther and therefore are not interpreted as staminodes. Presumed vestiges of the staminodes corresponding to those of the Epidendroideae and Vandoideae are differentiated in early developmental stages, but remain inconspicuous structures later on. The three-lobed rostellum originates entirely from the median carpel. The outstanding systematic position of the tribe Orchideae is briefly discussed.