Chin J Plan Ecolo ›› 2010, Vol. 34 ›› Issue (1): 89-99.DOI: 10.3773/j.issn.1005-264x.2010.01.012

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A review of the evolutionary and ecological significance of lever-like stamens

ZHANG Bo1, 2; SUN Shan1;ZHANG Zhi-Qiang3;LI Qing-Jun1*   

  1. 1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China; 2Graduate University of Chinese Academy of Sciences, Beijing 100049, China; and 3Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China
  • Online:2010-01-01 Published:2010-01-01
  • Contact: LI Qing-Jun

Abstract: We review the structural diversity and evolutionary significance of a type of highly modified stamen that is lever-like or spurred and can function as lever during pollination. Evolutionary changes of the androecium in stamen number and morphology often take place during floral evolution, shifting from pollen production to new functions. Lever-like stamens have been described in several subfamilies of Lamiaceae and six genera of Zingiberaceae. There are two types. One is derived from connective elongation and is largely structured by two parallel developed stamens; it occurs in the Lamiaceae, typically Salvia. The other is modified from one developed stamen and occurs in the Zingiberaceae. Both types have a similar role in pollination in that pollinators have to push the lower arm of the staminal lever into the corolla tube for nectar and consequently load pollen on their backs; this is widely regarded as a mechanism of facilitating crossing-pollination and can affect reproductive success via precise pollination, pollen dispensing, etc. These stamens independently originated and evolved in different taxa. For example, there have been three independent evolutions in Salvia, and this has been presumed a key innovation driving species’ radiation within the genus. Future research is needed at the levels of both macro- and micro-evolution to fully understand evolutionary and ecological significance of lever-like stamens.