钝叶柃不同性别花的花部形态与传粉特征比较

Abstract

Flowering and pollination are important processes for reproduction of flowering plants,especially for the dioecious ones.Until now,flowering and pollination of Eurya plants have not been reported.Plants of this genus are described as dioecy in most of the literatures.Hermaphrodite flowers had only been reported in Eurya japonica Thunb..In our recent study,gender variation was found in Eurya obtusifolia H.T.Chang,as well as hermaphrodite flowers.After primary investigation of its floral structure and function gender,floral morphology and pollination characteristics were studied in detail through field and lab.observation. We set four plots in Beibei District,Chongqing(one plot at Xishanpin,three others at Jinyun Mountain).Indicators related to floral morphology and pollination,such as size of flower structures,flower orientation,pollen viability,stigma receptivity,pollen resistance to water,pollen amount and nectar volume of a single flower,as well as flowering dynamics,the pollinator species,and the pollination behavior were observed or determined.The bagging experiments were also carried out at the same time.The findings were as below. E.obtusifolia is a species with short florescence,small but massive blossoms and highly-synchronous flowering,the color and the smell of both sexes of which are the same.The pollination of this species is mainly entomophilous,which depend on two Apidae insects.Insect pollination is relatively dominating compared to wind pollination(anemophilous),which plays a tiny role. The male and the female of E.obtusifolia have some similar characteristics,but also have many obvious differences in respect of the floral morphology and the pollination character.The main differences are as follows: 1) The male flower is lantern-like with non-reflexed petals,while the female flower is radial with reflexed petals.2) The male possesses significantly bigger flowers compared to the male.3) The flower apex of the males tends to vertically downwards,while which of the female tends to obliquely downward to the terminal of the branch.4) The female flower lives longer than the male one.Accordingly,the pollinators behave differently on two sexes.The gender variant individuals present some transitional traits between the male and the female.For E.obtusifolia,many features on the flowering and the pollination reflect its adaptibility to the dioecy sexual system to some extent. Morphological differences between the male and the female of E.obtusifolia have been resulted from various biotic and abiotic factors in surrounding,of which,pollinator and rain selection might play important roles.