STUDIES ON THE SPOROPHYTE MORPHOLOGY AND THE SPOROGENESIS OF BRYOPHYTES

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1. Five basic types of spore mother cell were recognized in meiotic division of bryophytes, which showed some close co-relations between the types and the taxonomic groups of high category. They include :(1) The monoplastidic, non-lobed spore mother cells which give rise to tetrahedrally arranged spore tetrads (Musci and Anthocerotae), (2) the polyplastidic, quadri-lobed spore mother cells forming tetrahedrally arranged spore tetrads : each spore contains polyplastids (Subclass Jungermanniidae of Hepaticae), (3) the polyplastidic, no-lobed spore mother cells producing tetrahedral spore tetrads (Marchantia), (4) the polyplastidic, non-lobed spore mother cells producing bilateral spore tetrads (Conocephalum conicum), and (5) the polyplastidic, non-lobed spore mother cells producing linear spore tetrads (Conocephalumjaponicum).2. Detailed histological data were obtained for the sporogenesis of Oncophorus crispifolius as a representative of the acrocarpous mosses. Light and electron microscopic observations first showed (1) the amoeboid tapetum is also present in bryophytes, which has been known only in Solidago, Chrysanthemum, and Aster of angiosperms, and (2) a single layer of archesporium is formed in capsule, each cell of which undergoes 3 times cell divisions producing 8 spore mother cells ; namely a single archesporial cell produces 32 spores in this species. Successive stages of sporogenesis were first shown in micrographs which support the general process of sporogenesis explained in textbook for mosses.