Comparative cypsela morphology in Campuloclinium DC. and contributions to Eupatorieae tribe (Asteraceae) systematics

Abstract

Cypselae anatomical studies have helped to understand the evolution and classification of some groups within Asteraceae. In Eupatorieae, there are many uncertainties about the Campuloclinium circumscription. There are currently two classifications for the genus, and still no consensus for their delimitation. Since structural studies have contributed to the delimitation of groups in Asteraceae, we studied the cypselae of Campuloclinium, searching how the pericarpial taxonomic features could enlighten the genus classification. We studied the fruits of eleven species of this genus through morphological and anatomical observation. Our results showed relevant features to the classification of Campuloclinium and its closely related groups. The stipitate cypsela together with other diagnostic characters are relevant to delimitation of this genus within of Eupatorieae. The trichomes present in cypselae have taxonomic proved to be a possible diagnostic character for the genus, and the six-celled trichomes are essential to distinguish C. campuloclinioides and C. hirsutum. The combination of phylogenetic and structural studies may lead to future research on the delimitation of Campuloclinium and its clades and understand how the stipitate cypselae and the phytomelanin layer evolve in Eupatorieae.

Key words
anatomy; fruit; Gyptidinae; pericarp; phytomelanin layer; stipitate cypsela