Over 70% of flowering plants are hermaphroditic, with male and female parts in the same flower. Hermaphroditism is cost-effective because a common investment in reward and attractive structures yields benefits through both male and female reproductive success. However, the advantage is accompanied by an increased risk of self-pollen deposition, which is disadvantageous for both self-compatible and self-incompatible species. Hermaphroditic plants reduce self-pollen deposition by separating sporophylls (male and female reproductive parts) either spatially (herkogamy) or temporally (dichogamy). In movement-assisted dichogamy, both sporophylls are involved in a coordinated motion, where they move in opposite directions. However, the effectiveness of this adaptation in reducing self-pollen deposition may be compromised at the point when the sporophylls cross each other and are close enough to interfere, resulting in a transition phase problem. The solution to this problem lies in the details of the spatiotemporal dynamics of the sporophylls in relation to their reproductive maturity. We studied these details across the floral lifetime of a protandrous shrub Clerodendrum infortunatum (Lamiaceae), in rainforest fragments of the Western Ghats, India. We took photos of flowers at regular time intervals and measured sporophyll angles from the images. We also carried out a field experiment to determine stigma receptivity. The findings suggest that the effectiveness of dichogamy is maximised through two properties of the transition phase: physical resistance to self-pollen deposition by narrow stigma lobe opening, and chemical non-receptivity of the stigma during this phase. This study emphasises the importance of accessory adaptations in movement-assisted dichogamy to tackle the transition phase problem, which is inherent in this particular form of dichogamy.

中文翻译：

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运动辅助双歧症中孢子粉的时空动态微调：硬皮油囊的研究

超过70％的开花植物是雌雄同体的，雌雄同花。雌雄同体是具有成本效益的，因为对奖励和有吸引力的结构的共同投资通过男女生殖成功而产生收益。然而，该优点伴随着自花粉沉积的风险增加，这对于自相容和自相容的物种都是不利的。雌雄同体的植物通过在空间上（herkogamy）或在时间上（dichogamy）分离孢子叶（雄性和雌性生殖部分）来减少自花粉的沉积。在运动辅助双歧症中，两个孢子叶都参与协调运动，它们在相反方向上运动。然而，当孢子叶彼此交叉且距离足够近以至于干扰时，可能会降低这种自适应降低自花粉沉积的效果。解决该问题的方法在于，将孢子叶的时空动态与其繁殖成熟度相关。在印度西高止山脉的热带雨林碎片中，我们研究了原灌木灌木Clerodendrum infortunatum（Lamiaceae）整个花期的这些细节。我们以固定的时间间隔为花朵拍照，并从图像中测量孢子囊角度。我们还进行了现场实验以确定柱头的接受度。研究结果表明，通过过渡阶段的两个属性，双歧症的有效性得以最大化：狭窄的柱头瓣开口对自花粉沉积的物理抵抗力，以及在此阶段柱头的化学非接受性。这项研究强调了在运动辅助双歧症中辅助适应对解决过渡阶段问题的重要性，这在这种特殊形式的双歧症中是固有的。