Late stages of anther development and anther attributes in Microepidendrum differs from other genera of Epidendrum alliance (Orchidaceae)

Abstract Late floral ontogeny is studied in representative species of the genera of Epidendrum alliance to re-examine the systematic position of the controversial Microepidendrum subulatifolium . Series of late floral stages were sampled from M. subulatifolium , Caularthron bilamellatum , Barkeria uniflora and Epidendrum ciliare . The samples were prepared for scanning electronic microscopy. Several characters that were observed during late floral development in Barkeria , Epidendrum and Caularthron in the Epidendrum alliance such as curvature of the column, wings on the column, ontogeny of the anther, conspicuous striate ornamentation of the cuticle of the epidermis of the anther wall, characteristic actinocytic stomata and their location on the anther, shape and number of caudicles, and shape of clinandrium, are not shared with M. subulatifolium . These characters suggest that the correct systematic position of M. subulatifolium might be in the Encyclia alliance as previously suggested. We determined the polarity of character states for three attributes in the Epidendrum alliance. The polarity regarding the degree of fusion between the lip and column within the Epidendrum alliance goes from free lip in Caularthron , lip adnate to column-foot in Orleanesia , lip attached only to the base of the column and the rest of the lip appressed to the column-part but not united with it in Barkeria , and a completely fused lip and column in Epidendrum . For curvature of the column, the trend goes from initially straight in early developmental stages to arcuate. Striae in the cuticle of the epidermis of the anther evolve from smooth to sparse to very conspicuous with radial and parallel cells.