title: Functional implications of the staminal lever mechanism in Salvia cyclostegia (Lamiaceae).
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, The Chinese Academy of Sciences, Menglun Town, Mengla County, Yunnan, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Regine
authors.initials: R
authors.lastname: Classen-Bockhoff
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Zhang
authors.forename: Shan
authors.initials: S
authors.lastname: Sun
authors.forename: Yan-Jiang
authors.initials: YJ
authors.lastname: Luo
authors.forename: Qing-Jun
authors.initials: QJ
authors.lastname: Li
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology; D035264:Flowers / Q000033:anatomy & histology* / Q000502:physiology*; D005638:Fruit / Q000254:growth & development; D054817:Pollination / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D027544:Salvia / Q000033:anatomy & histology* / Q000502:physiology*; D012639:Seeds / Q000254:growth & development; D013997:Time Factors