已有的资料将柃木属(Eurya)描述为严格的雌雄异株植物, 性别变异现象极为少见。目前仅在柃木(E. japonica)和钝叶柃(E. obtusifolia)等少数种类中报道过两性花的存在。近几年笔者发现细枝柃(E. loquaiana)存在性别变异现象, 性别变异株上具有不同性别类型的花。该文从单花和植株水平分析了细枝柃的性别表达特性, 并对不同类型花的花部构件生物量分配进行比较分析。结果表明, 细枝柃具有6种类型的花, 从单花水平上看, 细枝柃性别有雌性、雄性及两性3种类型; 细枝柃性别在植株水平上体现较为复杂, 有雌株, 雄株, 雌花和两性花同株, 雄花和两性花同株, 雌雄异花同株及雌花、雄花、两性花同株6种类型; 在细枝柃花部构件生物量分配中, 雄花(包括雄株花和变异株雄花)花部构件生物量分配中雄蕊生物量的分配低于雌花(包括雌株花和变异株雌花)中雌蕊生物量的分配; 两性花中, 雄蕊生物量分配低于雌蕊, 这是其优化资源分配的手段, 进而获取最大适合度收益。

The genus of Eurya Thunb. was described as strictly dioecious, and the gender variation was extremely rare. Until now, bisexual flowers had only been reported in a few species such as E. japonica and E. obtusifolia. We recently found gender variation in E. loquaiana with different types of flowers. Here, we analyzed sex expression characteristics at the flower and plant levels and compared reproduction allocation between different kinds of flowers. E. loquaiana had six types of flowers: pistillate flower, staminate flower, pistillate flower with staminode, staminate flower with pistillode, hermaphrodite flower, and sterile flower. At the flower level, the genders of E. loquaiana were female, male, and bisexual; the gender at the plant level was complicated. E. loquaiana had six gender types: gynoecius and roesious, gynomonoecy, and romonoecy, monoecious and trimonoecious; Stamen biomass allocation was less in male flowers (including the male plant flowers and gender variant plants) than pistil biomass allocation in female flowers (including the female plant and gender variant plants). In bisexual flowers, the stamen biomass allocation was less than the pistil biomass allocation. This is a means to optimize its resource allocation and thus obtain the most fitness benefits.