Bi- (to tri-) seriate stylar sweeping hairs are well-known from both genera (Eremothamnus, Hoplophyllum) of Eremothamneae (Asteraceae-Cichorioideae), and their assumed exclusive occurrence has been used in defining the tribe. In order to proof the phylogenetic/ taxonomic relevance of this character, I comprehensively studied genera of all tribes with respect to the occurrence of multi-seriate hairs. I describe for the first time bi- to even multi-seriate stylar hairs in the Hyaloseris clade (Stifftioideae-Stifftieae), in Oldenburgieae (Carduoideae), and in Wunderlichieae (Wunderlichioideae), formerly placed in a broadly circumscribed Mutisieae. The clusters of two to variable numbers of hairs, tightly linked together by their longitudinal cell walls, differ in the length of the tips of the individual cells, which remain separate during ontogeny and in the extent to which they cover the stylar branches and the stylar shaft. Stifftia exhibits papillate epidermal cells at the dorsal flanks of the stylar branches arranged in a line. On the basis of this observation, one can imagine that bi- to multi-seriate hairs result, if the walls of adjacent cells remain tightly linked during further elongation growth. Although the bi- to multi-seriate hairs are homoplasious, such hairs are not found in sister clades. Depending on their length and location on the styles, the bi- to multi-seriate stylar hairs are involved either in a brushing mechanism, in a pump mechanism, or in a combination of a brushing and a deposition mechanism of secondary pollen presentation.
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15 December 2015
Bi- to Multi-Seriate Stylar Hairs in Eremothamneae, Oldenburgieae, Stifftieae, and Wunderlichieae (Asteraceae)
Claudia Erbar
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Systematic Botany
Vol. 40 • No. 4
December 2015
Vol. 40 • No. 4
December 2015
Carduoideae
Cichorioideae
secondary pollen presentation
Stifftioideae
Wunderlichioideae