背景:假花或“假花”是多花单位,在形式和功能上类似于单生花。在过去的一个世纪中,“假花”一词已被应用于各种形态上不同的花朵,从那些容易注意到的小花到衍生的小花,单个花朵变得几乎无法区分的单位减少。尽管最初主要受到植物学家的钦佩,假单胞菌在被子植物中的多样性和广泛分布已经使它们成为进化和发育比较研究的一个有趣的话题。
方法:这篇综述综合了有关假象生物学的历史和当前概念。我们的首要目标是建立一个明确的,假药的操作定义和解开围绕该术语的常见术语误解。我们的第二个目标是总结有关假草的形态和发育多样性的知识,并将其嵌入现代系统发育框架中。最后,我们想提供一个全面的概述,对进化和生态的重要性,为未来的研究概述。
结论:对假虫的理解发生了多次变化,反映了对其“花状”品质的三种不同解释:发育(结构相似),形象(形式和功能相似)和系统发育(被子植物花和裸子植物中雌雄同株的生殖芽之间的同源性)。这里,我们建议将术语“假花”缩小为多花的花朵,形式类似于同动花,即在结构上被细分为华丽的外围和生殖中心。根据这个定义,至少在41个被子植物家庭中独立进化。在开花植物的所有主要谱系中反复获得的假草,表明发育限制之间的重复相互作用(花朵很小,分生关系条件)和选择压力,例如传粉者和/或环境条件的要求。
Pseudanthia or \'false flowers\' are multiflowered units that resemble solitary flowers in form and function. Over the last century the term \'pseudanthium\' has been applied to a wide array of morphologically divergent blossoms, ranging from those with easily noticeable florets to derived, reduced units in which individual flowers become almost indistinguishable. Although initially admired mostly by botanists, the diversity and widespread distribution of pseudanthia across angiosperms has already made them a fascinating topic for evolutionary and developmental comparative studies.
This
review synthesizes historical and current concepts on the biology of pseudanthia. Our first aim is to establish a clear, operational definition of pseudanthium and disentangle common terminological misconceptions surrounding that term. Our second aim is to summarize knowledge of the morphological and developmental diversity of pseudanthia and embed it within a modern phylogenetic framework. Lastly, we want to provide a comprehensive overview on the evolution and ecological importance of pseudanthia and outline perspectives for future studies.
The understanding of pseudanthia has changed multiple times and reflects three different interpretations of their \'flower-like\' qualities: developmental (similarity in structure), figural (similarity in form and function) and phylogenetic (homology between angiosperm flowers and monoecious reproductive shoots in gymnosperms). Here, we propose to narrow the term pseudanthium to multiflowered blossoms resembling zoophilous flowers in form, i.e. in being structurally subdivided in a showy periphery and a reproductive centre. According to this definition, pseudanthia sensu stricto evolved independently in at least 41 angiosperm families. The recurrent acquisition of pseudanthia sensu stricto in all major lineages of flowering plants indicates repeated interactions between developmental constraints (smallness of flowers, meristematic conditions) and selective pressures, such as demands of pollinators and/or environmental conditions.