Comparative anatomy and morphology of leaves between C3 and C4 species in Panicum

Abstract

Anatomical and morphological structures of leaf blades were compared between C3 and C4 species in Panicum. Inter-specific variation of stomatal density, longitudinal vein density and mesophyll thickness was highly correlative either plus or minus within respective groups. The two groups could not be distinguished by a single character, since the variation ranges overlapped each other. However, the quantitative relations between vein density and the other two characters differentiated the two groups well. In C3, stomatal density seemed to be a primary factor for regulating water balance, while in C4 vein system was considered to be important for the regulation. The species with intermediate photosynthesis behaved similar to the C3 species. In the C3 group, correlative variation was observed between leaf width, leaf angle and the three characters mentioned above. Variation of light-receiving area due to the changes of width and angle of leaf blades was considered to be one of the adaptive strategies of this group. Increase of light-receiving area was in connection with the thinning of leaves. On the other hand, in the C4 correlations between length, width and angle of leaves were low. Such loose character correlation may be achieved by its efficiency of CO2 utilization and its well developed vein systems. Besides, NAD-me type species tended to have relatively lower stomatal and vein densities as compared with the other decarboxylation types in this group. © 1985 Annals of Botany Company.