Pollen morphology of Brazilian species of verbesina L. (Heliantheae - Asteraceae)

Abstract

There are nine species of the plant genus Verbesina in Brazil, which are distributed in the Northeast, Center-West, Southeast and South regions of the country. The objective of the present study was to describe the pollinic morphology of eight of these species to better characterize them and evaluate potential species-level taxonomic characters. Acetolysed pollen material was measured within seven days under light microscopy, while non-acetolyzsed pollen grains were used for scanning electronic microscopy. The pollen grains were found to be oblate-spheroidal, medium-sized, isopolar, monads that are 3-colporate with a subtriangular amb, a small polar area, a long colpus, a lalongate endoaperture, a caveate exine and an echinate sexine. Although the shape of the pollen grains of these Brazilian species of Verbesina is homogeneous, some attributes were observed to be useful for characterizing the species, such as exine thickness, distance between spines and side of the apocolpus.