Journal Article

Functional implications of the staminal lever mechanism in <i>Salvia cyclostegia</i> (Lamiaceae)

Bo Zhang, Regine Claßen-Bockhoff, Zhi-Qiang Zhang, Shan Sun, Yan-Jiang Luo and Qing-Jun Li

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 107, issue 4, pages 621-628
Published in print April 2011 | ISSN: 0305-7364
Published online February 2011 | e-ISSN: 1095-8290 | DOI:
Functional implications of the staminal lever mechanism in Salvia cyclostegia (Lamiaceae)

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry


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Background and Aims

Flower morphology and inflorescence architecture affect pollinator foraging behaviour and thereby influence the process of pollination and the reproductive success of plants. This study explored possible ecological functions of the lever-like stamens and the floral design in Salvia cyclostegia.


Flower construction was experimentally manipulated by removing either the lower lever arms or the upper fertile thecae of the two stamens from a flower. The two types of manipulated individuals were intermixed with the control ones and randomly distributed in the population.

Key Results

Removing the sterile lower lever arms significantly reduced handling time per flower of the main pollinator, Bombus personatus. Interestingly, this manipulation did not increase the number of flowers probed per plant visit, but instead reduced it, i.e. shortened the visit sequence of the bumble-bees. Both loss of staminal lever function by removing lower lever arms and exclusion of self pollen by removing upper fertile thecae significantly reduced seed set per flower and seed set per plant. Both the manipulations interacted significantly with inflorescence size for the effect on female reproductive output.


Though the intact flowers demand a long handling time for pollinators, the reversible staminal lever is of advantage by promoting dispersal of pollen and thus the male function. The particular floral design in S. cyclostegia contributes to the floral constancy of B. personatus bumble-bees, with the lower lever arms acting as an optical cue for foraging cognition.

Keywords: Adaptation; Bombus personatus; experimental flower manipulation; floral constancy; floral design; foraging behaviour; geitonogamy; Salvia

Journal Article.  5234 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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