Huang Shuang-Quan
College of Life Sciences, Wuhan University, Wuhan 430072, China.
New Phytol. 2003 Feb;157(2):357-364. doi: 10.1046/j.1469-8137.2003.00676.x.
• Staminate flowers of andromonoecious species are thought to be produced to increase reproductive success through enhancing male function or diverting resources from unneeded pistils to fruits. This does not explain why andromonoecy occurs within genera with monoecy, since staminate flowers of monoecious plants can also serve these functions. • Here the male allocation of staminate and perfect flowers was measured in the annual herb Sagittaria guyanensis ssp. lappula , an andromonoecious species in a predominantly monoecious genus. Staminate flowers contained anthers that were larger and more numerous than those of perfect flowers, and their petals were also larger. This contrasts with most investigations where staminate flowers typically have equal or lower investment in male structures than perfect flowers. • Seed set was not significantly different between bagged and open-pollinated flowers. Pollinator observation and a pollen-dyeing experiment indicated visits to the flowers rarely occurred. • The presence of functional stamens in perfect flowers could be selected to allow reproductive assurance in case of inadequate pollination in andromonoecious species, rather than as a mechanism for optimal resource allocation.
• 雄全同株物种的雄花被认为是通过增强雄性功能或从不需要的雌蕊向果实转移资源来提高繁殖成功率而产生的。但这无法解释为什么在具有雌雄同株的属中会出现雄全同株现象，因为雌雄同株植物的雄花也能起到这些作用。
• 在此，对一年生草本植物矮慈姑（Sagittaria guyanensis ssp. lappula）——一个主要为雌雄同株属中的雄全同株物种——的雄花和两性花的雄性资源分配进行了测量。雄花中的花药比两性花的更大、数量更多，其花瓣也更大。这与大多数研究结果相反，在大多数研究中，雄花在雄性结构上的投入通常与两性花相等或更低。
• 套袋花和开放授粉花的结实率没有显著差异。传粉者观察和花粉染色实验表明，花朵很少有访花情况发生。
• 两性花中功能性雄蕊的存在可能是为了在雄全同株物种授粉不足的情况下确保繁殖，而不是作为一种优化资源分配的机制。
