Pollen morphology of Combretaceae from Thailand and its taxonomic significance

Abstract

The pollen morphology of 30 taxa from six genera of Thai Combretaceae, including one species each of Anogeissus and Calycopteris, two species each of Lumnitzera and Quisqualis, 11 species of Combretum and 13 species of Terminalia (including one introduced species), was investigated to determine its taxonomic signifi cance. The pollen samples were acetolyzed and investigated under light and scanning electron microscopy. Pollen morphology of Thai Combretaceae was described, compared and discussed along with its taxonomic implications. The taxonomic signifi cance of pollen morphological characters for Thai Combretaceae is limited. The pollen grains were found to be monads, radially symmetrical, isopolar, small- to medium-sized, heterocolpate (tricolporate alternating with subsidiary colpi). The taxa studied can be divided into two groups and nine subgroups according to the fusion of subsidiary colpi at the polar area and the exine sculpturing patterns. However, this grouping is not congruent with the taxonomic classification of the family based on morphological as well as molecular data.