Davis Charles C, Endress Peter K, Baum David A
Department of Organismic and Evolutionary Biology, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA 02138, USA.
Curr Opin Plant Biol. 2008 Feb;11(1):49-57. doi: 10.1016/j.pbi.2007.11.003. Epub 2008 Jan 22.
Flowers exhibit tremendous variation in size (>1000-fold), ranging from less than a millimeter to nearly a meter in diameter. Numerous studies have established the importance of increased floral size in species that exhibit relatively normal-sized flowers, but few studies have examined the evolution of floral size increase in species with extremely large flowers or flower-like inflorescences (collectively termed blossoms). Our review of these record-breakers indicates that blossom gigantism has evolved multiple times, and suggests that the evolutionary forces operating in these species may differ from their ordinary-sized counterparts. Surprisingly, rather than being associated with large-bodied pollinators, gigantism appears to be most common in species with small-bodied beetle or carrion-fly pollinators. Such large blossoms may be adapted to these pollinators because they help to temporarily trap animals, better facilitate thermal regulation, and allow for the mimicry of large animal carcasses. Future phylogenetic tests of these hypotheses should be conducted to determine if the transition to such pollination systems correlates with significant changes in the mode and tempo of blossom size evolution.
花朵在大小上呈现出巨大的差异（超过1000倍），直径从不到一毫米到近一米不等。众多研究已证实，在花朵大小相对正常的物种中，花朵增大具有重要意义，但很少有研究探讨花朵极大或具花状花序（统称为花簇）的物种中花朵增大的进化过程。我们对这些破纪录者的综述表明，花簇巨型化已多次进化，并表明在这些物种中起作用的进化力量可能与其普通大小的同类物种不同。令人惊讶的是，巨型化似乎并非与大型传粉者相关，而是在以小型甲虫或腐肉蝇为传粉者的物种中最为常见。如此大的花簇可能适应了这些传粉者，因为它们有助于暂时困住动物，更好地促进体温调节，并能模仿大型动物尸体。未来应进行这些假设的系统发育测试，以确定向这种传粉系统的转变是否与花簇大小进化的模式和速度的显著变化相关。
