Institut für Biologie, Morphologie und Systematik der Phanerogamen, Freie Universität Berlin, Berlin, Germany.
PLoS One. 2012;7(8):e41121. doi: 10.1371/journal.pone.0041121. Epub 2012 Aug 20.
Stamen movements can be understood as a mechanism influencing pollen presentation and increasing outbreeding success of hermaphroditic flowers via optimized male function. In this study we experimentally analyzed the factors regulating autonomous and thigmonastic (triggered by flower visitors) stamen movements in eight species of Loasaceae. Both types of stamen movements are positively influenced by light and temperature and come to a virtual standstill in the dark and at low temperatures (12°C). Pollen presentation is thus discontinued during periods where pollinators are not active. Overall stamen presentation increases with increasing flower age. Contrary to expectation, no geometrical correlation between the floral scale stimulated and the stamen fascicle reacting exists, indicating that the stimulus is transmitted over the receptacle and stamen maturation dictates which and how many stamens react. Thigmonastic stamen presentation is dramatically accelerated compared to autonomous movement (3-37 times), indicating that the rate of stamen maturation can be adjusted to different visitation schedules. Flowers can react relatively uniformly down to stimulation intervals of 10-15 min., consistently presenting comparable numbers of stamens in the flower c. 5 min. after the stimulus and can thus keep the amount of pollen presented relatively constant even under very high visitation frequencies of 4-6 visits/h. Thigmonastic pollen presentation dramatically reduces the overall duration of the staminate phase (to 1/3(rd) in Nasa macrothyrsa). Similarly, the carpellate phase is dramatically reduced after pollination, down to 1 d from 4 d. Overall flower longevity is reduced by more than 2/3(rds) under high visitation rates (<3 d versus 10 d under visitor exclusion) and depleted and pollinated flowers are rapidly removed from the pool. Complex floral behaviour in Loasaceae thus permits a near-total control over pollen dispensation schedules and floral longevity of the individual flower by an extraordinary fine-tuning to both biotic and abiotic factors.
雄蕊运动可以被理解为一种机制，通过优化雄性功能来影响花粉展示并提高雌雄同体花的异交成功率。在这项研究中，我们实验分析了调节 8 种卫矛科植物自主和触发（由花访客触发）雄蕊运动的因素。这两种类型的雄蕊运动都受到光照和温度的积极影响，在黑暗和低温（12°C）下几乎停止。因此，在传粉者不活跃的时期，花粉展示会停止。整体而言，雄蕊展示随着花龄的增加而增加。与预期相反，被刺激的花萼片和反应的雄蕊束之间不存在几何相关性，这表明刺激是通过花托传递的，并且雄蕊成熟决定了哪些和多少雄蕊反应。触发的雄蕊展示比自主运动快得多（3-37 倍），这表明雄蕊成熟的速度可以根据不同的访问时间进行调整。花可以在刺激间隔 10-15 分钟的情况下相对均匀地反应，在刺激后约 5 分钟内始终呈现可比数量的雄蕊，因此即使在非常高的访问频率（4-6 次/小时）下，也可以使花粉展示的数量相对恒定。触发的花粉展示大大缩短了雄花阶段的整体持续时间（在 Nasa macrothyrsa 中缩短至 1/3）。同样，授粉后雌花阶段也大大缩短，从 4 天缩短至 1 天。在高访问率下（访客排除下的 3 天与 10 天相比），整体花寿命缩短超过 2/3（rds），并耗尽和授粉的花朵迅速从池中移除。因此，卫矛科植物的复杂花行为通过对生物和非生物因素的精细调整，允许近乎完全控制花粉分配时间表和个体花的花期。
