Studies in the Family Ranunculaceae: Embryology ofThalictrum javanicum Blume

Abstract

Summary The anther wall consists of an epidermis, endothecium, two middle layers and a glandular tapetum. Cytokinesis in the microspore mother cells is of the simultaneous type. The pollen grains are shed at the 2-celled stage. The ovule is anatropous, bitegminal and crassinucellar. Triads are more common than the tetrads and the latter are either linear or T-shaped. The chalazal megaspore functions and produces an 8-nucleate embryo sac of the Polygonurn type. The 3 antipodal cells are large and persist after fertilization, but remain uninucleate. The endosperm is nuclear and centripetal wall formation commences from the micropylar end. The cells of the mature endosperm are thick walled and uninucleate. Endosperm vesicles are seen in some of the embryo sacs. The zygote divides by a transverse wall. Variations exist in the behaviour of the terminal cell (ca) indicating the coexistence of other types of embryogeny. In many ovules, however, the embryogeny is of the Onagrad type. The seeds are small and the testa is formed by the thickened outer epidermis of the outer and the inner epidermis of the inner integuments.