Understanding the systematic implications of Pollinium morphology of Aeridinae (Orchidaceae)

Abstract

Abstract Molecular phylogenetic studies have suggested major clades in the subtribe Aeridinae of Orchidaceae. However, systematic morphological charaters is still lacking. We carried out this study on the pollinium morphologies of subtribe Aeridinae with emphases on the aperture types and the pollinium sculpture to find out their systematic signification in light of a molecular phylogeny. The results indicate that most species have cleft type and few with porate type or none. All samples in this study have a complete tectum exine and most with psilate surface impling an advanced position of Aeridinae in Orchidaceae. Exine sculpture characters are consistent in each clades except Cleisostoma clade and Phalaenopsis clade. It has a somewhat clear changing tendency in consist with the molecular phylogeny with few exceptions. Gastrocohilus and Trichoglottis clades are supported by its non - flabellate pollinium, psilate bulgy sculpture, and irregular shape of individual units of pollinium. However, no distinguishing pollinium characteristics is found between them. Conclusionarily, exine sculpture characters are not systematic but useful characters in determining major systematic groups in subtribe Aeridinae.