中文摘要：

花的起源是植物学和进化生物学中的重要问题,长期以来备受关注.近年来,分子系统学、进化发育生物学和基因组学的兴起和蓬勃发展,不仅为花起源的研究带来了新思路,而且更新了人们对该问题的认识.基于这些领域的新进展,人们不仅纠正了前人在理论和模型中的错误、提出了可验证的新假说,而且揭示了花发育MADS-box基因的进化对花起源的贡献.然而,已有研究只能笼统地解释花作为一个整体是如何起源的,并不足以全面揭示花和花器官起源的根本机制.本文在总结与花和花器官起源相关理论和假说的基础上,介绍人们对花和花起源问题的新见解,探讨花起源机制的复杂性,指出花的起源和基本结构的建立涉及诸多＂小＂的关键性状的改变,认为只有对这些性状进化的分子机制进行研究才能真正揭示花起源的内在原因.

英文摘要：

The flower is a characteristic feature of angiosperms. The innovation and diversification of the flower significantly improve the reproductive efficiency and environmental adaptation of angiosperms, and thus contribute to the great success of angiosperms in terrestrial ecosystem. How the flower originated is a major aspect of Darwin＇s ＂abominable mystery＂ of the origin and rapid diversification of angiosperms, and has long been a basic question of evolutionary biology and botany with intense investigations. Over the past two centuries, many theories and hypotheses have been proposed to explain the origin of the flower based on a broad spectrum of multidisciplinary research involving comparative morphology, paleontology, anatomy, and developmental biology. However, the answer to how the flower originated has remained controversial because the phylogeny of the seed plants was poorly resolved and the molecular basis of flower development was not unraveled. In 2005, Science posed this question as one of the 125 most challenging scientific questions in a special issue to commemorate the 125 th anniversary of the journal, implying that the study of the process and mechanisms of the origin of the flower is still a hot topic of current evolutionary biology and botany. In recent years, thanks to the rise and rapid progress in molecular phylogenetics, evolutionary developmental biology（evo-devo）, and genomics, new ideas have been brought and our knowledge on the origin of the flower has been updated. Now, it is generally believed that（i） the flower is a determinate, compressed, and bisexual reproductive axis, which consists of perianth, androecium, and gynoecium from the outer to the inner;（ii） the flower did not originate abruptly but evolved gradually, with bisexuality being the first step, followed by the compression of reproductive axis and the evolution of the floral determinacy, and the floral structural elements originated at different evolutionary stages; and（iii） the floral MADS-box genes tha