Original paper

Styles in Carduoideae (Asteraceae) – diversity in the uniformity

Erbar, Claudia; Eichelser, Carolin; Mögerle, Svenja

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Plant Diversity and Evolution Volume 132 No. 1 (2020), p. 1 - 42

published: Mar 26, 2020
published online: Sep 28, 2018
manuscript accepted: Mar 22, 2018
manuscript received: Feb 28, 2018

DOI: 10.1127/pde/2018/0132-0087

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ArtNo. ESP145013201000, Price: 29.00 €

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Abstract

Based on detailed studies on style morphology of all tribes (Dicomeae, Oldenburgieae, Cardueae, Tarchonantheae) and subtribes (in Cardueae) of the subfamily Carduoideae, we establish 10 new style types in view of shape, bifurcation and distribution of stylar hairs and stigmatic tissue in continuation with the already established style types in basal Asteraceae (Erbar & Leins 2015a). The carduoid style type characterized by a collar of hairs is found in five variants, namely as Arctium-, Carduus-, Centaurea-, Macledium/Cyanus- and Staehelina-style type. They differ in the position of the collar of hairs (directly beneath the stylar branches or further down on the stylar shaft) and the arrangement of the stigmatic papillae (over the entire inner branch surface or inversely U-shaped by adhesion of the stylar branches or loss of receptivity). The Arctium-, Carduus-, Centaurea-, and Macledium/Cyanus-style types are repeatedly found in the subtribes of the Cardueae, whereas the Staehelina-, Berardia-, and Cousinia-style types are restricted to one genus. In the Dicomeae, the Dicoma- and the Macledium/Cyanus-style type are found; the both Oldenburgia species investigated have each their own type. Due to the unisexuality of their flower, no style type can be established in the Tarchonantheae. The mechanisms of secondary pollen presentation are less diverse as the style types because most of the types exhibit a collar of hairs, crucial for the special pump mechanism in most Cardueae. The deviating Berardia combines pumping and brushing. In Dicomeae, Oldenburgieae, and Tarchonantheae, a pump mechanism of secondary pollen presentation is inferred.

Keywords

Asteraceae • Carduoideae • style morphology • SEM • histology • secondary pollen presentation