The synstigma is a structure formed by clusters of two to several stigmas, whether in the same or between different flowers. Although rare in angiosperms, synstigmas are found in c. 500 out of the c. 750 Ficus spp. (Moraceae). This floral structure is associated with fig-fig wasp pollinating mutualism. The synstigma structure and pollen tube pathways were studied in six Ficus spp. from Ficus section Americanae to test the hypothesis that the synstigma allows pollen grains deposited on a stigma to emit pollen tubes that can grow laterally and fertilize surrounding flowers. Syconia containing recently pollinated stigmas were collected and dissected, and the stigmas were processed for analyses with light and scanning and transmission electron microscopy. The arrangement of the synstigmas across species can be spaced or congested, with the number of stigmas per synstigma ranging from two to 20. Contact between the stigmas in a synstigma occurs by the intertwining of the stigmatic branches and papillae; their union is firm or loose. The pollen tube grows through live cells of the transmitting tissue until reaching the ovule micropyle. Curved pollen tubes growing from one stigma to another were observed in five out of the six species studied. The curvilinear morphology of pollen tubes probably results from competition by pollen between the stigmas composing a synstigma via chemotropic signals. The synstigma appears to be a key adaptation that ensures seed production by flowers not exploited by the fig wasps in actively pollinated Ficus spp.

中文翻译：

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概要将无花果变成一朵大花

柱头是由两个到几个柱头的簇形成的结构，无论是在相同的花还是在不同的花之间。尽管在被子植物中很少见，但在c中发现了茎线结。500分c。750榕属 （桑科）这种花的结构与无花果黄蜂的授粉共生有关。在六个榕属植物中研究了剑突的结构和花粉管通道。从美洲榕科为了检验以下假设，即“长梗”允许花粉粒沉积在“长柄”上，从而发出可以横向生长并为周围花朵施肥的花粉管。收集并解剖包含最近已授粉的柱头的Syconia，并处理柱头以进行光分析，扫描和透射电子显微镜检查。跨物种的柱头的排列可以是间隔的或拥挤的，每个柱头的柱头数范围为2到20。他们的联合是坚定的或松散的。花粉管通过传播组织的活细胞生长，直至到达胚珠。在所研究的六个物种中，有五个发现了从一个柱头到另一个柱头的弯曲花粉管。花粉管的曲线形态可能是由于花粉之间通过趋化性信号构成柱头的柱头之间的竞争而产生的。该总柄似乎是一个关键的适应方法，可确保在未授粉的无花果黄蜂未利用的花朵中产生种子榕属