THE FINE STRUCTURE OF THE GRASS GUARD CELL

Brown, W. V., and Sr. C. Johnson. (U. Texas, Austin.) The fine structure of the grass guard cell. Amer. Jour, Bot. 49 (2): 110–115. Illus. 1962.—An electron microscopic study of 16 species of grasses classified in 10 tribes and 5 subfamilies has revealed some hitherto unknown facts about guard-cell structure. In species of 3 subfamilies, but not in the Festucoideae, there are membranes on the guard cells overarching the stoma. In the Festucoideae, the membrane is rudimentary or absent and is associated with a different cross-sectional shape of the guard cell. The central canal through the thick-walled region of the guard cell is structurally quite complex. The wall between the central canal and the subsidiary cell is thin and lacks plasmodesmata. There are plastids but no developed chloroplasts in grass guard cells. Mitochondria are abundant, but vacuoles are undetectable. At the ends of the guard-cell pair, the wall between them is incomplete and the protoplasts are confluent.