SOME EMBRYOLOGICAL OBSERVATIONS ON POPULUS TOMENTOSA CARR .——Ⅱ. About the structures of ovule and embryo sac, the process of ferti- lization and the development of embryo
This paper is the second part of Some embryoloical observations on Populus tomentosa Carr. the structure of ovule,development of embryo sac, fertilization and development process of embryo were studied. The relations between outside characteristics of catkin and development of ovule during pre-pollination and post-pollination were given.The ovary consists of two carpels. The stigma is 4-lobed. The style is open; placenta basal with 2 - 4 ovules;usualy only 1-2 ovules fertile. Ovule anatropous with funiculus well developed, unitegmic, crassinucellar-the megaspore tetrad linear, porogamy. Aater pollination the double fertil ization will be completed in 40 hours to 6 days. The endosperm is of "nuclear type" . The embryogeny conforms to the simplified "Crucifer type" .Integument characteristics, development type of embryo sac, the way of fertilization and embryogeny were discussed.