Embryological Studies on Phellodendron amurense

Phellodendron amurense Rupr. is a dioecious tree with abortive carpels in the staminate flower and abortive stamens in the pistillate flower. The anther wall conforms to the basic type. The tapetum, of which each cell contains 2 or more nuclei in the later stages, is the glandular type. The cytokinesis of the microspore mother cells in meiosis is the simultaneous type. The microspores are arranged in a tetrahedral tetrad. The mature pollen grains are of the 2-celled and 3-celled types. The ovary is 5-locular. The placentation is axile. The ovule is biteguminous, crassinucellate and anatropous. The female archesporium is multicellular. The megaspore tetrad is linear arrangement or occassionally T-shaped. The functional megaspore in the linear tetrad is the one at the chalazal end. The development of the embryo sac is the polygonum type. The double fertilization belongs to the premitotic type of syngamy. The embryo develops to conform the chenopodiad type. The endosperm develops to be the nuclear type. In the later stage ,a secondary endosperm develops in the periphery of the endosperm , while the inner endosperm cells degenerate and disintegrate.