七子花的繁殖生物学研究

A Study on the Reproductive Biology of Heptacodium miconioides

对国家 2级保护植物七子花 (Heptacodiummiconioides)的开花、传粉与结实等繁殖特性进行了研究。结果显示 :七子花的花无梗 ,由多轮紧缩呈头状的聚伞花序组成顶生圆锥花序 ,多数花序开两轮花 (基轮和中轮 ) ,少数只开基轮花。自花传粉的比例高 ,花后 4h的柱头花粉多超过 6 0粒 ,8h的柱头可多达 14 2粒 ,其中近 1/ 3的花粉萌发 ,少数能到达子房。每个子房仅 1枚胚珠可育 ,其平均结实率为 4 0 6 % ,上轮花的开花会影响下轮花的结实率 ,降低幅度可达 34 8% ,早开花的结实也会影响迟开花的结实。表明七子花的结实率很低 。

We studied the reproductive biology of Heptacodium miconioides ,a national protected plant species in China. The results showed that there were no pedicels in the flowers of Heptacodium miconioides and terminal panicle was composed of several constrictive capitate cymes. It usually flowered with the basal and middle whorls, and some flowered with only the basal whorl. Self pollination was high in reproduction. There were over 60 pollens loading on the stigma 4 hours after flowering, and pollens amounted to 142 at most 8 hours after flowering. At least 1/3 pollens germinated and a few of them could reach ovary in which only 1 ovule could develop. The average seed set of developed ovule was 40 6% and the seeding of middle whorl would influence that of basal whorl, its decrease rate was 34 8% and the seeding of basal whorl would influence that of middle whorl. All the results suggested that the seed set in Heptacodium miconioides was mainly caused by resource limitation.