Abstract Astragalus is with nearly 3000 described species the largest genus of flowering plants. So far analyses of pollen characters have only been conducted for a few species of the groups within the genus. Here we analyse pollen grains of 22 species representative for Astragalus section Hymenostegis using scanning electron microscopy. We found the basic shape of the pollen grains to be oblate-spheroidal and apertures to be tricolpate as for other eudicots. The sculpturing pattern of the exine is micro-reticulate. Pollen grains show low morphological variation among different species of this section, but differences occur between sections of the genus. We conclude that the vast morphological differentiation that occurred during the rapid radiation of section Hymenostegis was not accompanied by comparable differentiation in pollen morphology.

中文翻译：

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黄芪科豆科植物的花粉形态及其系统意义评价

摘要 黄芪是有花植物中最大的属，有近3000种。迄今为止，仅对该属内的少数几个物种进行了花粉性状分析。在这里，我们使用扫描电子显微镜分析了代表黄芪部分 Hymenostegis 的 22 种花粉粒。我们发现花粉粒的基本形状是扁球形，孔是三叶草，与其他双子叶植物一样。外壁的雕刻图案是微网状的。本节不同种间花粉粒形态变异较小，但属间节间存在差异。我们得出结论，在 Hymenostegis 部分快速辐射期间发生的巨大形态分化并没有伴随花粉形态的可比分化。