Floral micromorphology in 'Epidendrum secundum complex' (Orchidaceae, Asparagales)

Abstract

Epidendrum Lindl. is the largest genus of orchids in the Neotropics; E. secundum and E. xanthinum belong to the entitled "E. secundum complex" and both species have disjoint distribution in the Espinhaço Range and Serra do Mar in Brazil. The taxonomic delimitation problems in the complex are due to the large polymorphism as the size and shape of flowers, resulting in discussion about the existence of more than one species. This work aims to answer the following questions: 1) Considering E. secundum and E. xanthinum distinct species, what are the main floral micromorphological differences between these lineages? 2) If differences between both species are found, what is the potential role of such divergent characters in the evolution of E. secundum and E. xanthinum as different species? Therefore, we will study the floral micromorphology of E. secundum and E. xanthinum from usual scanning electron techniques (SEM). The existence of more than one species will be discussed following the principles of integrative taxonomy. In a major context, it is believed that these data, with the combination and integration of morphology and anatomy to molecular data and reproductive biology, may help to clarify the evolutionary issues and relationship between groups of species with taxonomic uncertainties.