Floral anatomy and ultrastructure of Lepanthes calodictyon, L. saltatrix and L. tentaculata (Orchidaceae).

Background: Previous studies have shown that the ultrastructure and histochemistry of flowers give insight into the pollination mechanisms of orchid species. The microscopic features of species within the Pleurothallidine subtribe are poorly understood. In this study, we investigated three Lepanthes species: L. calodictyon, L. saltatrix and L. tentaculata. These species have a similar flower morphology that is distinct from that of the other representative of the genus.

Results: Our analyses revealed the presence of features usually associated with myophily. The papillae of lips and petals of the L. calodictyon group were rich in lipids and proteins, which were correlated with high metabolic activity. Furthermore, the ultrastructural and morphological features were similar to those observed in other fragrance-emitting orchid species.

Conclusions: Histochemical, ultrastructural and morphological features of the papillae on the surface of the lips and petals of examined taxa indicate that the papillae are osmophores.