Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
Ann Bot. 2013 Nov;112(8):1477-93. doi: 10.1093/aob/mcs252. Epub 2012 Dec 13.
Most angiosperms present flowers in inflorescences, which play roles in reproduction, primarily related to pollination, beyond those served by individual flowers alone. An inflorescence's overall reproductive contribution depends primarily on the three-dimensional arrangement of the floral canopy and its dynamics during its flowering period. These features depend in turn on characteristics of the underlying branching structure (scaffold) that supports and supplies water and nutrients to the floral canopy. This scaffold is produced by developmental algorithms that are genetically specified and hormonally mediated. Thus, the extensive inflorescence diversity evident among angiosperms evolves through changes in the developmental programmes that specify scaffold characteristics, which in turn modify canopy features that promote reproductive performance in a particular pollination and mating environment. Nevertheless, developmental and ecological aspects of inflorescences have typically been studied independently, limiting comprehensive understanding of the relations between inflorescence form, reproductive function, and evolution.
This review fosters an integrated perspective on inflorescences by summarizing aspects of their development and pollination function that enable and guide inflorescence evolution and diversification.
The architecture of flowering inflorescences comprises three related components: topology (branching patterns, flower number), geometry (phyllotaxis, internode and pedicel lengths, three-dimensional flower arrangement) and phenology (flower opening rate and longevity, dichogamy). Genetic and developmental evidence reveals that these components are largely subject to quantitative control. Consequently, inflorescence evolution proceeds along a multidimensional continuum. Nevertheless, some combinations of topology, geometry and phenology are represented more commonly than others, because they serve reproductive function particularly effectively. For wind-pollinated species, these combinations often represent compromise solutions to the conflicting physical influences on pollen removal, transport and deposition. For animal-pollinated species, dominant selective influences include the conflicting benefits of large displays for attracting pollinators and of small displays for limiting among-flower self-pollination. The variety of architectural components that comprise inflorescences enable diverse resolutions of these conflicts.
大多数被子植物在花序中呈现花朵，花序在繁殖中发挥作用，主要与传粉有关，超出了单个花朵的作用。花序的整体繁殖贡献主要取决于花冠状部的三维排列及其在开花期间的动态。这些特征反过来又取决于支撑和供应花冠状部水分和养分的基础分支结构（支架）的特征。这种支架是由遗传指定和激素介导的发育算法产生的。因此，在被子植物中表现出的广泛花序多样性是通过改变指定支架特征的发育程序而进化的，这反过来又改变了促进特定传粉和交配环境中繁殖性能的冠部特征。然而，花序的发育和生态方面通常是独立研究的，限制了对花序形态、生殖功能和进化之间关系的全面理解。
本综述通过总结花序发育和传粉功能的各个方面，促进了对花序的综合认识，这些方面使花序进化和多样化成为可能并指导其进化和多样化。
开花花序的结构包括三个相关的组成部分：拓扑结构（分支模式、花的数量）、几何结构（叶序、节间和花梗长度、三维花排列）和物候学（开花率和花期、雌雄异熟）。遗传和发育证据表明，这些组成部分在很大程度上受到定量控制。因此，花序进化沿着多维连续体进行。然而，拓扑结构、几何结构和物候学的某些组合比其他组合更为常见，因为它们特别有效地发挥了生殖功能。对于风媒传粉的物种，这些组合通常是对花粉去除、运输和沉积的物理影响的冲突的妥协解决方案。对于动物传粉的物种，主要的选择影响包括大展示吸引传粉者的利益与小展示限制花内自交的利益之间的冲突。构成花序的各种结构成分使这些冲突能够得到不同的解决。
