Trichome diversity in the subtribe Leiboldiinae (Vernonieae, Asteraceae)1

Abstract

Abstract Trichome diversity in vegetative and reproductive structures of species from the subtribe Leiboldiinae (Vernonieae, Asteraceae) are described and illustrated. Based on scanning electron microscopy, we identified two main trichome types, glandular and eglandular. The eglandular trichomes were further subdivided into unicellular (papillae, conical, and filiform) and multicellular (flagelliform, uniseriate with three variants in the apical cell, and twin hairs). Additionally, the latter showed variation in the number of basal cells, which is most likely related to the type of structure supporting those cells. A species identification key, based on trichome diversity, is provided. We discuss the taxonomic importance of trichomes for delimiting of closely related species and as generic diagnostic characters. In the first case, the presence of glands on the cypsela was a diagnostic character of Leiboldia, and in the second case, the presence of twin hairs on the cypsela and phyllaries of Leiboldia guer...