Probable functions of calcium oxalate crystals in different tissues of the edible aroids (Xanthosoma and Colocasia spp.) in Nigeria

Abstract

Representatives of seven major edible aroid accessions were screened for calcium oxalate using standard histochemical methods. All the accessions were noted to contain calcium oxalate in the forms of raphide bundles and intra-amylar crystals. The crystals were widely present in all parts of the plants including spongy mesophyll of the leaves, laticifers in the midrib and petioles, cortex of the roots and in the starch granules. The crystals occurred in the starch granules as intra-amylar structures and in the vegetative tissues as raphide bundles located in parenchymatous idioblasts. The most remarkable aspect of the histochemistry of this ergastic substance in the edible aroids is the high concentration of the raphide bundles around the root apical meristems. This suggests that the crystals of calcium oxalate serve a protective function in the root of these taxa. Their occurrence in starch granules imply that they are stored products and as such of value to the plants.

Keywords: Root apical meristem, calcium oxalate crystals, Colocasia, laticifers, mesophyll, raphide bundle, raphide idioblast, Xanthosoma

African Journal of Biotechnology Vol. 12(25), pp. 3952-3956