Abstract
In order to discuss the physiological significance of the existence of Ca oxalate crystals at the pulvinus of rice plants, the amount of Ca oxalate or Ca was estimated anatomically or chemically at different leaves, and different parts of each leaf with their development. The results are summarized as follows; 1. Many types of Ca oxalate crystals which differed in shape and water content were observed at the pulvinus. Among them the tetragonal dihydrate crystal was of the abundant type (Fig. 1). 2. Crystals at the pulvinus of upper and more active leaf were more abundant and larger than those at the pulvinus of basal leaf (Fig. 3-5). 3. Calcium oxalate crystals seems to start its deposition at the pulvinus of leaf when it emerged from the previous leaf sheath, after that their number and size increased rapidly with the expansion of the leaf, and then gradually decreased with a deformation of the crystals of tetragonal type as the leaf senescenced (Fig. 2-5). 4. The concentration of HCl soluble Ca of the basal part of leaf sheath containing pulvinus gradually decreased as the leaf age proceeded (Fig. 7). 5. It was suggested from these results that at least one of roles of Ca oxalate at pulvinus may be a temporary storage of Ca and/or oxalic acid rather than the exclusion of the toxic effect by oxalic acid.
