Pollen morphology of species of Graphistylis B. Nord. (Asteraceae) of Brazil

Abstract

This paper presents the results of a palynological study of the species of Graphistylis that were segregated from Senecio (s.l.) (Senecio sect. Dichroa) and that are all endemic of Brazil. These species are found in mountainous regions of the states of Espirito Santo, Minas Gerais, Parana, Rio de Janeiro, Sao Paulo and Santa Catarina. The pollen grains of eight species were acetolyzed and analyzed and photographed using light microscopy. Unacetolyzed pollen grains were analyzed and photomicrographed using scanning electron microscopy. The current study undertook a palynologically analysis of Graphistylis in order to obtain information useful for making a better ranking of these genus. The results show medium-sized pollen grains that were oblate spheroidal or prolate spheroidal and subtriangular amb and tricolporate. The pollen grains possessed lalongate endoapertures with a median constriction and the presence of costa in only two species. The exine is echinate with a varying number of spines in the apocolpium region around the central spine in polar view. The spines are short with basal perforations at varying distances. Although the morphology of the pollen of species of Graphistylis is very similar, multivariate analysis highlights the importance of quantitative traits in distinguishing species.