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Anatomy of the vegetative organs as subsidy to the taxonomy of Geissospermum (Apocynaceae - Rauvolfioideae)

Abstract

Considering the interspecific morphological similarities in Geissospermum and the difficulty of collecting fertile specimens of the genus, this work aimed to provide potential diagnostic anatomical characters for the group based on the analysis of vegetative organs. For this, stem and leaf samples of G. argenteum Woodson, G. laeve (Vell.) Miers, G. reticulatum A.H. Gentry, G. sericeum Miers, and G. urceolatum A.H. Gentry were collected from exsicates deposited at the herbaria HAMAB, INPA and MG and processed according to standard plant anatomy techniques. The studied species were then compared on a binary matrix of characters submitted to methods of grouping (UPGMA) to obtain a phenogram and, posteriorly, a dichotomous identification key. Our phenotype analysis showed that the most similar anatomically species are G. argenteum with G. sericeum, G. laeve with G. reticulatum, and G. urceolatum being the most distinct species in the genus. Our results show that the anatomy contributed to the identification of Geissospermum, even in the absence of reproductive organs. The epidermal cell shape, persistence of trichomes, brachycleral arrangement, contour and vascularization of the petiole were the most important features to the recognition of taxa within the taxa.

Key words:
Amazonia; Aspidospermeae; Gentianales; Atlantic forest

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