The floral morphology and ontogeny of some Chinese representatives of orchid subtribe Orchidinae

Abstract

The flower structure and development of ten species in six genera of the orchid subtribe Orchidinae are described and illustrated by scanning electron micrographs. Particular attention is given to the structure of the gynostemium, which for most species is interpreted from ontogenetic data. All the species studied here share a series of features, e.g. the sequence of tepal and anther initiation, the shape and position of the anther, the presence of auricles and basal bulges, the three-lobed condition of the median carpel apex and the lateral lobes of the median carpel embracing the basal ends of the thecae. However, the form and structure of the three carpel apices are most varied in the later development stages or in the adult flower. The genus Hemipilia shows a series of peculiar characters that are quite different from those of the other genera in Orchidinae. The peculiar structure and development of the viscidia in both Amitostigma and Neottianthe indicate that both of them are different from other genera in Orchidinae. The adult floral morphology shows that the genera Galearis and Chusua are not congeneric with Orchis. The separation of the lateral lobes of the rostellum in most genera studied here as well as in the Brachycorythis group from South Africa suggests that this is the ancestral state in the subtribe Orchidinae. In contrast, the conjoining of lateral lobes in Dactylorhiza and Orchis is suggested as a derived character.