无梗五加的开花特点

Flowering Characteristics of Acanthopanax sessiliflorus

对野生无梗五加（Acanthopanax sessiliflorus）的开花特征进行了观察研究,结果表明：无梗五加单朵花的花期为9～10 d,花粉寿命为3～4 d,花柱在花开后逐渐伸长,柱头二裂、干燥型;同一花序内的花朵在3～4 d内逐渐开放,晚开的花朵散粉时早开的花朵花柱仍未伸长,因此,花药与柱头之间存在空间间隔和时间间隔,同一花序内的各花朵之间难于相互传粉;按照杂交指数,其繁育系统属于异交、部分自交亲和、需要传粉者.依据P/O数据,其繁育系统属于专性异交;无梗五加没有自发的自花传粉现象,自然条件下也没有无融合生殖现象,没有传粉者活动就不能座果.

An experiment was conducted to observe the flowering characteristics of Acanthopanax sessiliflorus. Results show that the duration of a single flower of A. sessiliflorus with a pollen viability of about three to four clays can last nine to ten days, and the pistil recipient phase starts from elongated style and bilobed stigma. In one inflorescence, all flowers blossom grad- ually within three or four days, and when the later flowers are in male phase （ anther dehiscence） , the earlier flowers are still undeveloped into female phase （pistil recipient phase）. Therefore, there are both temporal and spatial isolations between ♂ and ♀ organs within each flower of A. sessiliflorus. The breeding system of A. sessiliflorus, demanding for pollinators, is outcrossing and partially self-compatible according to the outcrossing index and is obligate xenogamy in terms of pollen-ovule ratio. There is no spontaneous self-pollination and agamospermy in A. sessiliflorus, so the fruit setting must depend on timely visiting of pollinators.