构树花部结构与传粉机制

Structure of Flowers and Pollination Mechanism of Broussonetia papyrifera

对桑科植物构树(Broussonetia papyrifera)雌、雄花的花部结构特征和传粉机制进行了研究,统计了构树的坐果率和结实率,并对构树雄蕊先熟的现象进行了讨论.结果表明:构树先花后叶,雄花先雌花开放;雄花柔荑花序,花小而多,每朵小花具有4个爆破性的花药,雄花发育初期雄蕊内折于花被中,花粉成熟时花丝平展,展开时强大的张力使花粉囊破裂,花粉弹出,雄花结构符合风媒传粉的特征.单个雄花序的花粉量约为6×108粒,小花朵数约217朵;雌花聚合成球状,花柱长丝状,柔软弯曲,表面具微绒毛,变态花萼2枚,具毛;构树坐果率高达100%,结实率为81.89%,果实为聚花果.

The structure of male and female flowers and the pollination mechanism of Broussonetia papyrifera were studied.The fruit setting and seed setting rates of B.papyrifera were analyzed statistically.The phenomena of protandry in B.papyrifera were also discussed.It was found that the flowers opened before leaves,male flowers opened before female flowers.The male flower is small with four anthers and has catkin inflorescence.Puckered stamens are surrounded by the perianth in the early growing stage of male flowe...