Taxonomic studies on Musci, with special reference to the morphology of sporocytes and their relationships to higher taxonomic ranks

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Investigations of sporogenesis were conducted on 33 species of mosses belonging to 7 orders and 17 families in order to search any characters worth of taxonomic recognition of higher categories. Observations were focused especially on the morphology of sporocytes: whether they are spherical or four-lobed and the meiotic stage at which cytoplasmic four-lobing is recognized under photomicroscope with regard to the materials fixed with Carnoy's solution and stained by 0.5% aceto-orcein. Four-lobed sporocytes were observed only species belonging to the family Polytrichaceae except those of Bartramiopsis. The investigation on Oligotrichum is indispensable to evaluate four-lobed sporocytes as taxonomic importance of higher rank. Cytoplasmic lobing was observed at and later stages of second division of meiosis in many acrocarpous mosses, while it was recognizable even at prophase-I in many pleurocarpous mosses. Sporocytes of Sphagnum and Andreaea are spherical to ovoid, never four-lobed; but spore-tetrads of Andreaea are very characteristic having the spores which have the walls strongly wrinkled and are closely packed in the wall of sporocyte, and spores quickly swollen and becoming larger soon after liberation from the sporocyte wall. It seems to be of taxonomic importance that the development of sporophytes of Sphagnum and Andreaea is already completed when they exposed from perichaetial leaves, since this phenomenon is of nature known in hepaticae.