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

Abstract

Abstract—Circumscription of genera in the tribe Vernonieae is complex due to overlapping morphological features among genera such as Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus. These genera have been segregated from the genus Vernonia s. l., but their classification remains questionable because they lack clear diagnostic characters to contribute to this classification. Several studies have demonstrated the importance of the anatomy of cypselae for classification in Compositae; cypselae provide diagnostic characters for some genera. We studied the anatomy of the cypselae, including pericarp, callus, carpopodium, and pappus of Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus, evaluating their potential for clarifying systematic problems in these genera. Our study demonstrated the cypselae features are uniform, and they do not contribute diagnostic characters useful in generic circumscription; however, cypselae anatomical characters do segregate some species. Our data also suggest that Chrysolaena, Echinocoryne, Lepidaploa, and Lessingianthus should be circumscribed in a single genus Lepidaploa.