Studies on the Photosynthetic Tissues in the Leaves of Cereal Crops. : V. Comparison of the mesophyll structure among seedling leaves of cereal crops

[摘要] Anatomical observations were made among seedling leaves of cereal crops. The crops used in this observation were classified systematically to the following three groups. Bambusoid group····rice (Oryza sativa and Oryza glaberrima), Panicoid group····Italian millet (Sataria italica), common millet (Panicum Crus-galli), grain sorghum (Andropogon sorghum) and maize (Zea mays) and Festucoid group····rye (Secale cereale), barley (Hordeum vulgare), wheat (Triticum vulgare) and oats (Avena sativa). In these crops, most of the mesophyll cells were so-called the arm-cells having several protuberances. According to the direction of cell elongation and protuberance development, the mesophyll cells of cereal leaves were divided into the following types: tubular palisade cells (P-type), longitudinally elongated arm-palisade cells (LP-type), transversely elongated arm-palisade cells (TP-type) and rachymorphous arm-cells (R-type). The TP- type cells were found only in the rice species, whereas the other types were found in the almost every crop of the panicoid and festucoid groups. The P- and LP-type sells occur in the outer layer of the mesophyll and the R-type cells occur in the inner layer of the mesophyll. There were large differences among these crops in size of the mesophyll cells. The size becomes larger in the order, bambusoid, panicoid, festucoid. Size of the mesophyll cells was positively correlated to thickness of the mesophyll and length of the epidermal cells, whereas the number of stomata per unit leaf area was found to be negativbly correlated. In the leaves of the rice species, palisade-like arrangement of TP-type cells was observed in longitudinal sections. In the leaves of the panicoid and festucoid groups, palisade-like arrangement of LP-type cells was observed in transections. Orientation of the long axes of palisade cells, appearing in transections, were closely related to their position in the mesophyll. In the outer layer of the mesophyll, the palisade cells were oriented with their long exes at right angles to the leaf surface. The palisade cells around the vascular bundles were oriented in a radiating manner. Panicoid leaves having short interveinal distance and well-developed parenchymatic bundle-sheath, showed a distinct radial arrangement of the mesophyll cells. From this observation, the relationship between function and structure of the mesophyll was discussed.

[学科分类] 农业科学（综合）