• Studies of floral polymorphisms have focused on heterostyly, while stigma‐height dimorphism has received considerably less attention. Few studies have examined the reproductive biology of species with stigma‐height dimorphism to understand how factors influencing mate availability and pollen transfer are related to morph ratios in populations.
• Floral morphological traits, especially herkogamy and reciprocity, pollinator visitation, breeding system and spatiotemporal mate availability, are known to affect inter‐morph pollination and morph ratios in species with stigma‐height dimorphism. In this study, we investigated the presence of stigma‐height dimorphism and estimated morph ratios in four naturally occurring populations of Jasminum malabaricum. We quantified morph‐ and population‐specific differences in the abovementioned factors in these populations to understand the observed morph ratios.
• The positions of anthers and stigmas were characteristic of stigma‐height dimorphism, the first report of this polymorphism in the genus. All study populations were isoplethic, implying equal fitness of both morphs. Herkogamy was higher in the short‐styled morph, while reciprocity was higher between the long‐styled stigma and short‐styled anthers. Long‐ and short‐tongued pollinators were common floral visitors, and we observed no differences between morphs in spatiotemporal mate availability or pollinator visitation. Neither morph exhibited self‐ or heteromorphic incompatibility.
• The short‐styled stigma had lower reciprocity but likely receives sufficient inter‐morph pollen from long‐tongued pollinators, and also by avoiding self‐pollination due to higher herkogamy. These results highlight the importance of sufficient effective pollinators and floral morphological features, particularly herkogamy, in maintaining isoplethy in species with stigma‐height dimorphism.

中文翻译：

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高度的雌雄同体但互惠性较低，代表了茉莉花（Jasminum malabaricum）的等量种群，该种具有柱头高度双态性。

• 花卉多态性的研究主要集中在异质性上，而柱头高度二态性受到的关注则少得多。很少有研究检查具有柱头高度双态性的物种的生殖生物学，以了解影响配偶可用性和花粉转移的因素如何与种群中的形态比相关。
• 已知花形形态特征，尤其是雌雄同株和互惠，传粉者探访，繁殖系统和时空伴侣的可利用性，会影响具有柱头高度二态性的物种的形态间授粉和形态比率。在这项研究中，我们调查了四个天然茉莉花种群中柱头高度二态性的存在和估计的形态比。我们对这些人群中上述因素的形态和种群特异性差异进行了量化，以了解观察到的形态比率。
• 花药和柱头的位置是柱头高度二态性的特征，这是该多态性在属中的首次报道。所有研究人群均等容，表明两种形态的适应度相等。在短型花药中，Herkogamy较高，而长型柱头和短型花药之间的互易性较高。长舌和短舌的传粉者是常见的花访者，我们观察到时空伴侣的可利用度或传粉者访视的形态之间没有差异。两种变体均未显示出自身或异形不相容性。
• 短头柱头的互易性较低，但很可能从长舌传粉者身上得到足够的形态间花粉，并且还避免了由于较高的同源性而引起的自花授粉。这些结果凸显了足够有效的传粉媒介和花卉形态特征（尤其是雌雄同株）对于保持柱头高度二态性物种同等的重要性。