Study On The Embryology Of Caryopteris Mongholica Bunge

Caryopteris mongholica Bunge is belonging to Verbenaceae,Caryopteris.It is a endemic plant in mongolian plateau,mainly found in provinces of Hebei,Shanxi,Shanxi,Inner Mongolia,Gansu in china and some areas in Mongolia.C.mongholica is used for conservation of water and soil,with great economic value.The megasporogenesis,microsporogenesis,the development of female,male gametophyte,fertilization and the development of embryo,endosperm of C.mongholica were studied,through outside observation,measure and light microscopy of paraffin-sectioned material.The main results are as follows:1.Micro-,megasporogenesis and the development of male and femle gametophytes:The anther has four chambers and the development of anther wall is dicotyledonous type,which is composed of epidermis,endothecium,has one middle layer and glandular tapetum with two nucleate cells.The tapetum has dual origin.the cytokinesis of microspore mother cell in meiosis is simultaneous,and the tetrads are tetrahedral,occasionally isobilateral.The mature pollen grains are two-cells with three colpates.C.mongholica has two carpels in pistil and four locules in ovary,and axile placenta.The ovule is anatropous,unitegmic,and tenuinucellate.The archesporial cell lies under nucellus epidermis,which developes into functional megasporocyte.The megaspore tetrads are linear and the chalazal megaspore is functional.The embryo sacs belongs to Polygonum type.2. Fertilization and the development of embryo,endosperm:Double fertilization of C.mongholica is of the type of premitotic syngamy. The embryo development is of the onagrad type.The mature seed has no endosperm.3.The results show that embryological characteristics of C.mongholica is more similar to some plants in Labiatae.The embryological data so far available infer that the C.mongholica is closely related to Labiatae.So,we speculated that Labiatae and Verbenaceae may have the same original ancestor.