Density of Calcium Oxalate Crystals in 15 Prickly Pear Cultivated Species

Abstract

Recent studies have demonstrated differences in the type of calcium oxalate crystals among Cactaceae subfamilies and suggest the possibility of using the differences/similarities of calcium oxalate crystals to characterize species of this family. In this study, differences in the number of calcium oxalate crystals were evaluated for 15 prickly pear cultivated species of Opuntia and Nopalea genus, as a potential tool to discriminate among cactus species. Distribution of oxalates within cladodes was also analyzed. Results showed that density of calcium oxalate crystals was homogeneous at each cladode, both at the base, middle and top. However, number of crystals did differ between cultivated species. Number of calcium crystals ranged from 18 up to 57 for the studied varieties. This work makes an important contribution to the difficult task of discriminating prickly pear varieties or other cactus species, by assessing the density of calcium oxalate crystals.