Stamens and mimic stamens as components of floral colour patterns
published: Dec 19, 2006
Stamens of zoophilous plants are multifunctional floral organs which protect pollen against environmental stress, attract potential pollinators, attach pollen to the sites of secondary pollen presentation, or to the pollinator's body surface, and provide pollen as a reward for flower-visitors. Pollen-eating flower-visitors such as syrphid flies and pollen-collecting flower-visitors such as bees innately respond to visual and chemical cues of stamens and pollen prior to individual experience. Flowering plants presenting conspicuous stamens and pollen to attract pollinators incur numerous costs associated with visual exposure of pollen including investments for protection against solar radiation, pollen losses caused by wind, rain, and illegitimate flower-visitation, and pollen losses due to consumption of pollen by flower-visitors or pollinators. Many flowers use mimic stamens (e.g. staminodes, false stamens, yellow floral guides in the size and shape of anthers) and thus overcome these disadvantages. Several study cases focus on the benefits of signaling with mimic stamens in flowering plants having polymorphic flowers, distinct flowering phases, and hidden real pollen. The aim of this review is to illustrate the various cases in which flowering plants may benefit from attracting flower-visitors by means of mimic stamens.