Study On Embryology Of Exotic Invasive Plant Galinsoga Parviflora

This paper studies embryo development of Galinsoga parviflora by means of paraffin wax.The main content of this observation is the megasporgenesis and microsporgenesis,the development of male and female gametophyte, the fertilization, the development of embryo,endosperm as well and invasive ability of Galinsona parviflora. The main results are as follows:(1)Anther wall includes 4 layer,anther wall includes the epidermis, The development of anther wall is primitive type which is composed of epidermis, endothecium and amoeboid tapetum.The tapetum begins to vary at the stage of tetrad with the cytoplasm moving into the anther cell. The cytokinesis of microspore mother cell in meiosis is simuteneous and continuous, and the tetrad are tetrahedral. The mature pollen grain is 2-celled.(2) The ovary has 1 locule and there is 1 anatropous ovule in each locule. The ovule is unitegmic and tenuinucellatae. The megaspore mother cells are developed directly by a hypodermal archesporical cell whick undergoes meitotic division and forms a linear tetrad. The embryo sac is of Polygonum type.(3)The fertilization is of premitosis type. A sperm and egg cell fusion formation of homozygous; Another sperm and polar nucleus fusion formation of a primary endosperm.(4)The development of embryo belongs to Solanad type. The fertilized egg usually underwent a rest period before embarking on its first division. After the globular embryo, the heart-shaped embryo, and the fish-torpedo embryo developed the mature embryo.(5)Galinsoga parviflora is less demanding of the environment. In the city Harbin, the germination of the Galinsoga parviflora is very early, it's flowering and fruiting time is long, it's reproductive cycle is short. There is not the phenomenon of abortion for male and female gametophyte development. The structure of reproductive organs is simple, the reproductive efficiency is high and can produce many seed without dormancy. It's propagation distance is short and easily form a single excellent community. These features are that it will become an important factor in invasive plants.Based on field investigation and analysis of relevant literature, there is a new plant of galinsoga named Galinsoga quadriradiata to be found in the city Harbin.This paper enriches the biological data of Galinsoga parviflora, and it offers the oretical foundation for plant reproductive biology, it is also bring us the theoretical reference for prevention and the use of the Galinsoga parviflora.