Comparative Anatomy of Cypselae in the Complex Group Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus: Contributions to the Systematics of Vernonieae (Compositae)

Abstract

Vernonieae is known as the evil tribe due to its complex this tribe. This complexity is reflected in the genera of this tribe as Chrysolaena, Echinocoryne, Lepidaploa and Lessingianthus which, besides having many shared morphological characters, also possess an uncertain phylogenetic relationship. In26 groupsmorphology with great overlapping character status shared with many of Asteraceae, several anatomical studies have demonstrated the importance of the anatomy of the cypselae for the classification of the family, and these studies have contributed to the separation of the genera. In this way, we studied the anatomy of the cypselae of these four genera, evaluating their potential for solving thesystematic problems in this group. The pericarp, floral disk, carpopodium and pappus were analysed for the genera. Our study shows that the structural characteristics of the cypselae are uniform between the genera and that they cannot contribute to the separation of the same, although these characteristics contribute to the separation of some species. This result corroborates that the separation of these genera is uncertain. Although these genera were segregated from the ancient genus Vernonia s.l. its separation is still questionable, since to date there are not enough morphological and phylogenetic characters to contribute to this classification. Actually, the anatomy of the cypselae only contributes to the taxonomy of some of the species, since the presence of glandular trichome and idioblasts, lignification of the carpopodium exocarp and definition of ribs present taxonomic value only at specific level.