Differences in Mesophyll Structures between Temperate and Tropical Grasses

Abstract

Mesophyll structures of the flag leaves in temperate and tropical grasses were anatomically observed. The species used in this observation were grouped systematically in three subfamilies, the Festucoideae (13 species), Panicoideae (9 species) and Eragrostoideae (4 species). The P-type cells (palisade cells) and LP-type cells (longitudinally elongated arm-palisade cells) were found in many species of the temperate and tropical grasses, whereas the TP-type cells (transversally elongated arm-palisade cells) were not found in the tropical grasses. The temperate grasses have larger mesophyll cells in size than the tropical grasses. Size of the mesophyll cells was positively correlated with thickness of the mesophyll. Arrangement of mesophyll cells, appearing in transections, was divided into the following types; a) irregular arrangement, b) palisade-like arrangement at the abaxial layer of mesophyll, c) palisade-like arrangement at both abaxial and adaxial layers of mesophyll and d) radial arrangement. The former three, types were found in the temperate grasses, and the last type was found in the tropical grasses.