Morfologia das cipselas do complexo Chromolaena congesta (Asteraceae)

Abstract

The study of anatomical features proved to be very relevant to better understand the relationships within Asteraceae, at all taxonomic levels. The genus Chromolaena, tribe Eupatorieae, contains a small group of species, mostly typical of the Southern States of Brazil, which have an overlap of morphological characteristics that hinders their identification. This work aims to verify and compare anatomical characteristics of the fruits of nine, among ten species of the complex, informally called "group Chromolaena congesta". Thus, the species may have more diagnostic characteristics and narrower limits, facilitating their identification. To achieve this goal, the micromorphology and anatomy of the cypselas of the ten species of the complex were analyzed. The results show characteristics common to the tribe, subtribe and genus, such as the presence of phytomelanin between the external and internal mesocarp, continuously deposited and passing internally to the vascular bundle and biseriate non-glandular trichomes in all cypselas studied. The distribution of trichomes in cypselas was quite variable among the species, and the presence of glandular trichomes in some species helps to distinguish them from others. These characteristics can be compared in order to facilitate the identification of the species of the complex.