Pollen diversity in selected species of the tribe Chironieae (Gentianaceae Juss.) that occur in the Atlantic Forest, Brazil
Abstract
ABSTRACT Based on molecular data, the tribe Chironieae (Gentianaceae) is divided into three subtribes. This study aims to describe the pollen morphology of representatives of two of the three subtribes that occur in the Atlantic Forest in order to contribute to a better understanding of the palynology of these taxa and to clarify the taxonomy of the family: subtribe Chironiinae (Centaurium erythraea and Zygostigma australe) and subtribe Coutoubeinae (Coutoubea ramosa, C. spicata, Deianira chiquitiana, D. damazioi, D. erubescens, D. nervosa and D. pallescens). Botanical material was obtained from exsicates and treated by acetolysis for light microscopy. Pollen grains were measured and photomicrographed, and the results statistically analyzed. For SEM study, non-acetolyzed pollen grains were sprayed onto metal stubs. The results show that the pollen grains in Chironiinae are medium-sized, prolate-spheroidal or subprolate, 3-colporate, monads, with striate-reticulate ornamentation. In Coutoubeinae the pollen grains are large or medium-sized tetrads with aperture varying between 3-porate or 3-hemicolpates and the sexine microreticulate (D. erubescens) or varied reticulate (the other species). Pollen morphology proved to be an important tool for the systematics of the family since it corroborated the existing placement of species into subtribes based on molecular data.
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