Morphogenetic studies on excised leaves ofOsmunda cinnamomea: histological studies of leaf development in sterile nutrient culture

摘要

Leaf primordia ofOsmunda cinnamomeaL. explanted to a culture medium of simple composition at the end of three of their five seasons of development, complete their normal morphogenetic sequence but produce mature leaves of greatly reduced size. A histological study of the ground tissues of the rachis of cultured leaves reveals that, at least in these tissues, the size reduction results from a diminished cell number rather than from reduced cell elongation. It is apparent that, at every stage of development, cell division is greatly curtailed and that cell elongation begins precociously. Nevertheless, the pattern of development, including the distribution of mitotic activity at critical stages in the morphogenesis of the leaf, is normal. It is concluded that the effects of isolation upon leaves at this stage of development are quantitative ones upon the extent and duration of cell division and cell elongation.