类叶升麻(毛茛科)自花传粉机制

毛茛科类叶升麻(Actaea asiatica)有2种开花方式, 一种与同属其它植物相同, 花萼片在开花早期脱落, 花药远离柱头; 而另一种较为特殊, 能使该植物进行自花授粉, 即在花开放前, 花萼从花托上脱离, 但萼片并不张开, 部分雄蕊的花丝伸长, 将花药推入萼片和柱头之间, 收缩的花萼片将开裂的花药压在宽大的柱头上, 进而完成自花授粉。套袋实验结果表明, 类叶升麻自发自交具有很高的结籽率, 不具有孤雌生殖和风媒传粉。繁育系统估测分析结果显示, 类叶升麻自交亲和,为兼性自交的繁育系统。

Self-pollination Mechanism of Actaea asiatica (Ranunculaceae)

There are two flowering modes in Actaea asiatica (Ranunculaceae). In the first mode, the sepals are caducousand the anthers are physically isolated from the stigmas as in most out-breeding, bisexual species in this genus. Thesecond flowering mode leads to mechanical self-pollination (autogamy). The sepals do not open or fall off from the flower,but are only dletached from the floral receptacle. The staminal filaments elongate to push the anthers in between thestigma and the withered sepals. The latter press the dehiscent anthers onto the large stigma, which results in mechanicalautogamy. The results of our bagging tests showed that the highest seed set resulted from spontaneous self-pollination inA. asiatica, but no seed set was found as a result of apomixis or anemophily (via air currents). This species is obviouslyself-compatible and obligate autogamy.