Calcium oxalate crystals in plant communities of the southeast of the Pampean Plain, Argentina

Abstract

Calcium oxalate crystals (COC) are one of the most prevalent and widely distributed biomineralizations in plants. The aim of this work is to analyze and compare the data previously reported about the presence and production of COC in leaves of plant species from forests, wetlands and agroecosystems of the southeast of the Pampean Plain. Diaphanization, clearing of tissues with 50% sodium hypochlorite and cross sectioning of the leaves were realized. The material was mounted with gelatin-glycerin and COC were identified and described with optical, polarization and scanning electron microscopes. Crystal size and density were calculated. Calcification mainly occurred in leaf mesophyll. In terrestrial species, crystals were closely associated to vascular bundles, instead in aquatic species they were associated to aerenchyma. Druses, prisms and raphides were observed in the leaves of all species analyzed. Average crystals size was smaller in terrestrial species than aquatic ones (12 and 80μm respectively), but average crystal density was higher (246 and 23 crystals/mm2, respectively). These different patterns in COC production and distribution maybe related to taxonomical characteristics, the types of cells where crystals precipitate, their function and the differential transpiration rates, among other factors.