Sex System Study Of Nine Acer Plants In Zhejiang

Acer plants belong to Sapindales aceraceae,the tree and leaf shape of most species of Acer plants are beautiful,which are yellow or red before falling from the trees,and the plants have high ornamental value and are applicated universally in the garden.Acer plants have complex sex system,and studing the evolution of the system will contribute to understanding it of angiosperms.We studied 9 species of Acer plants in Zhejiang,and observed phenophase,inflorescence characteristics,sex ratio,floral morphology,flowering characteristics and pollen viability of the different genders in the different species,in order to understand the expression pattern of Acer plants sex and explore the evolution of the system.The main results are as follows:1.Througth observation on 9 species of Acer plants in2005 and 2006,they flowered one time every year and the inflorescences is lateral or at the top of shoots,the same inflorescence has male and Bisexual flowers,the types of flowers did not show obvious regularity,and the proportion of the number of bisexual flowers accounted for all flowers is 13.36%?28.44% ?The germination was in March,leaves openning and flowering were in late March to early April and end in the middle of April,fruit setting begun in late April and fruit mature and fallen off in late September,in mid October,the colour of leaves changed.The time of these progresses is almost consistent.In addition to Acer cinnamomifolium Hayata,the leaves of other species fallen off in early December.2.Except for A.davidii is hermaphrodite,the male and female function of other tested species is separate in time,and for the same plant,male and bisexual flowers open in a certain order,which can be divided intoprotogyny and duodichogamy.Male and hermaphrodite flowers are quite different in appearance and there are significant differences in the length of anther,filament,ovary and Column,but there is no difference between the length of petal,petal width and flower diameter.Bisexual flowers have complete male and female organs,while male flowers have anther and pistil which development incompletely;The anther of bisexual flower is normal,but it has not been cracked.The hermaphrodite flowers of Acer plants are hermaphrodite in morphology,but are female flowers in the actual function.It,s sex system is andromonoecy in morphology and functionally monoecious.3.Acer plants anthers had 4 pollen sacs,whose development was basic type.Male flower anther could normally cracking and powdering.Bisexual flowers stamens had no difference in early development with male flowers,mature anther tapetum was completely dissolved,fiber layer undergone secondary thickening and the outer tangential wall also occurred thickening,The inner wall of anther and connective did not occur normal programmed cell death,which resulted in the rip was not dry and anther didnot crack.The ovule and ovary of Male flowers gradually degraded in the functional megaspore period,mature ovary only had abortive ovule and two lobed stigma could be visible in morphology;Bisexual flower pistil development normally and formed eight nuclear embryo sac.Male flowers may evolved gradually from bisexual flowers and were a developmental structure of bisexual flower pistil complete abortion;The anther of hermaphrodite flowers did not crack,which was a developmental structure of not complete abortion.