植物生态学报 ›› 2009, Vol. 33 ›› Issue (1): 222-236.DOI: 10.3773/j.issn.1005-264x.2009.01.024

• 综述 • 上一篇    

花内雄蕊分化及其适应意义

任明迅()   

  1. 中国科学院武汉植物园,武汉 430074
  • 收稿日期:2008-05-21 接受日期:2008-07-08 出版日期:2009-05-21 发布日期:2009-01-30
  • 作者简介:E-mail: renmingxun@yahoo.com.cn
  • 基金资助:
    国家自然科学基金(30700089);生物多样性与生态工程教育部重点实验室开放基金(K0801)

INTRAFLORAL STAMEN DIFFERENTIATIONS AND THEIR ADAPTIVE SIGNIFICANCES

REN Ming-Xun()   

  1. Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
  • Received:2008-05-21 Accepted:2008-07-08 Online:2009-05-21 Published:2009-01-30

摘要:

对花内雄蕊存在显著分化的现象进行了分析与归纳, 总结了花内雄蕊分化的各种主要形式及其繁殖适应意义。“花内雄蕊分化”是指花内雄蕊与雄蕊之间存在显著分化的现象, 这一概念可以把二强雄蕊、四强雄蕊和异型雄蕊等以往单独进行研究的相关性状结合起来, 并明确区分了几种新的花内雄蕊分化形式, 以期更准确全面地认识这些相关性状的适应意义与进化。该文将花内雄蕊分化区别为花丝的分化、花药的分化、雄蕊合生的分化、雄蕊运动的分化、退化雄蕊5大类。花丝的分化主要是花丝长度的分化, 如四强雄蕊、二强雄蕊和单强雄蕊; 花药分化主要指花药颜色、花药与花粉粒大小和花药开裂时间等的分化; 雄蕊合生的分化主要体现为花内部分雄蕊合生而部分雄蕊离生; 雄蕊运动的分化指的是花内雄蕊在运动时间或方式上存在差异, 造成雄蕊处于不同的成熟阶段和位于不同的空间位置; 退化雄蕊则是花内部分雄蕊失去了生产花粉的繁殖功能, 通常也发生了花药形态上的巨大改变。异型雄蕊不仅存在花丝和花药的形态分化, 还存在着明显的功能分化, 是分化程度很高的一类特殊的花内雄蕊分化形式。一些特殊的繁育系统, 如异长花柱和镜像花柱等在种内不同个体上存在着不同形式的花内雄蕊分化。花内雄蕊分化在花内造成了多个不同的花药位置, 在很大程度上影响了雌雄异位程度, 对植物自交与异交水平、花内雌雄功能干扰等有着潜在作用; 花内雄蕊分化形成的多个不同空间位置的雄蕊还增加了对多种访花者的吸引与适应潜力, 有可能影响到访花者的类型与访花行为, 得以适应多种传粉者。此外, 花内雄蕊分化可将花粉逐渐分批次分发给访花者, 提高花粉散布效率, 可看成是“花粉呈现理论”所指的花粉装配与分发机制之一。现有的实验研究发现, 花内雄蕊分化能够吸引传粉者、保护正常花药和花粉、促进花粉散发(降低花粉竞争)、实行延迟自交和降低花内雌雄功能干扰等。花内雄蕊分化还缺少系统研究, 有些雄蕊分化形式如单强雄蕊和雄蕊运动的分化还没有针对性的实验揭示其适应意义, 鸭跖草科和某些豆科植物的雄蕊三型分化等现象也缺少进化适应意义的研究。花内雄蕊分化对植物雌性和雄性适合度可能不同的影响、如何与访花者相互作用、如何与其它花部特征一起影响植物繁殖过程等, 可能是这一领域值得今后优先研究的课题。

关键词: 雌雄异位, 异型雄蕊, 单强雄蕊, 雄蕊运动, 传粉, 花粉呈现理论

Abstract:

Intrafloral stamen differentiations have adaptive significances and possible effects on plant reproduction strategies and mating patterns. Intrafloral stamen differentiations, in which stamens in a flower differ distinctly in shape, size or color of filament and/or anther and normally in function, can be classified into five main types: filament differentiation (e.g., filament length differentiation), anther differentiation (e.g., differentiation in pollen viability and anther color or size), differentiation in growth pattern of stamens (e.g., some stamens grow fused and others separately), differentiations in stamen movement (e.g., stamens move at different time and are in different dehiscence stages and different spatial position), and staminodes (i.e., some stamens have lost the function of producing viable pollen and normally have a different shape). Heteranthery, which is mostly found in enantiostylous species with mirror-image flowers, is a special type of stamen differentiation in which filament length, anther size and color, and pollen viability all are so differentiated that the two kinds of stamens show different functions: feeding stamens (normally sterile, but provide nutrients that attract and feed pollinators) and pollinating stamens (produce viable pollen). In some special types of complex breeding systems such as heterostyly and enantiostyly, intrafloral stamen differentiations are also present and differentiation modes often differ among individuals. Intrafloral stamen differentiations cause various spatial positions of anthers in a single flower, which can affect the herkogamy (spatial separation of female and male organs) and dichogamy (temporal separation of female and male functions), and the modes and foraging activities of pollinators can also be greatly affected. Consequently, plant mating patterns such as levels of selfing and sexual interferences are modified. Stamen differentiation can increase plant fitness through presenting pollen in many small doses in differentiated stamens, which can greatly enhance pollen output in plants receiving many pollinator visits, as suggested by pollen presentation theory. So, intrafloral stamen differentiations can be seen as a kind of pollen packaging and dispensing mechanism. Some adaptive significances of stamen differentiations have been recognized, but specific functions of some types (e.g., monodynamous stamens, differentiations in stamen movement time and/or mode, and trimorphic differentiation of stamen in Commelinaceae and some plants of Fabaceae) need further illumination.

Key words: herkogamy, heteranthery, monodynamous stamens, stamen movement, pollination, pollen presentation theory (PPT)