野生桂花繁育系统的观察和研究

Observation and study on breeding system of wild Osmanthus fragrans

对湖南省浏阳市周洛村桂花峡、福建省长汀县官坊村石峰寨东北坡和南坡、浙江省龙泉市供村及张公桥和毛圩村6个野生桂花〔Osmanthus fragrans(Thunb.)Lour.〕居群中桂花单株的性别比例进行了统计,并对单性雄株和两性株的花部雌蕊形态、花粉粒数量和外部形态及花粉在柱头上的萌发情况进行了观察和比较。结果显示:6个居群中雄性比率差异较大(0～0.62),平均值接近0.5;其中,石峰寨东北坡和南坡居群的雄性比率最大(0.62),张公桥居群的雄性比率最小。两性株花的雌蕊发育正常,而单性雄株的花具有退化雌蕊的痕迹。不同居群及个体间每个花药的花粉粒数量存在一定差异,且单性雄株每个花药的花粉粒数量多于两性株,但差异均不显著(P>0.05)。单性雄株和两性株的花粉粒形态一致,花粉粒均为长椭圆形、极轴长16μm、具三沟和网状雕纹型表面纹饰;花粉均具有较高活力且均能在柱头上萌发。结合对木犀属(Osmanthus Lour.)其他种类的观察结果认为:桂花的繁育系统应属功能性的雄全异株,这种繁育系统可能为两性同体与雌雄异株间的过渡类型,在木犀属的其他种类中也能观察到雄全异株的存在。

The sex ratio of Osmanthus fragrans（Thunb.） Lour.individual of six wild populations in Guihua Gorge of Zhouluo Village in Liuyang County of Hu＇nan Province,northeast and south slopes of Shifengzhai of Guanfang Village in Changting County of Fujian Province and Gongcun Village,Zhanggongqiao and Maoweicun Village in Longquan County of Zhejiang Province was counted,and pistil morphology in flower,number and external morphology of pollen and pollen germination on stigma of unisexual males and hermaphrodites were observed and compared.The results show that male ratio of six populations has a great difference（0-0.62） with an average value of near 0.5,in which that of northeast slope and south slope populations of Shifengzhai is the biggest（0.62） and that of Zhanggongqiao population is the smallest.Hermaphrodite flower has a normally developed pistil,while unisexual male flower has a trace of pistillode.There is a certain difference in pollen number per anther among different populations and individuals,and those of unisexual males are more than those of hermaphrodites,but without significant difference（P0.05）.Pollen morphology of unisexual males and hermaphrodites is same all with oblong,polar axis of 16 μm,tricolpate and reticulate surface ornamentation.Pollens all have higher activity and can germinate normally on stigmas.Combined with observation results of other species in Osmanthus Lour.,breeding system of O.fragrans should be functional androdioecy,which may be a transition type between hermaphroditism and dioecism,and can be found in other species in Osmanthus.