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 with vascular bundles, while in aquatic species, they were associated with aerenchyma. Druses, prisms, and raphides were observed in the leaves of all species analyzed. Average crystal size was smaller in terrestrial species than aquatic ones (12 and 80 μm, respectively), but average crystal density was higher (246 and 23 crystals/mm 2 , respectively). These different patterns in COC production and distribution may be related to taxonomical characteristics, the types of cells where crystals precipitate, their function, and the differential transpiration rates, among other factors.

Where did the water come from? Wetlands and shallow lakes in semi‐arid dunefields from South America during the Pleistocene–Holocene transition

“…This interpretation is based on facies models that show a sequence of carbonate facies, from calcrete, palustrine deposits to lacustrine muds, that represent successive sub-environments from permanently subaerial lake margins, marginal areas with fluctuating lake levels to a permanent lake setting, respectively (Alonso-Zarza, 2003: p. 114). Here, the formation of iron plaques, calcium oxalate crystals and cylindrical concretions, within the fluctuating or palustrine area, involves the presence of hydrophytes with welldeveloped root systems (Metcalfe, 1985;Sundby et al, 1998Sundby et al, , 2003Alonso-Zarza, 2003;Khan et al, 2016;Altamirano et al, 2018). Such Fe-rhizoconcretions have been recognized in environments such as Saharan dunes, and related to Pleistocene shallow water bodies (Felix-Henningsen, 2000), whereas Ca-rhizoliths associated with periods of relatively humid conditions in drylands are described from northwest China (Li et al, 2015a(Li et al, , 2015bSun et al, 2019bSun et al, , 2021Sun et al, , 2022.…”

Anatomía foliar de especies predominantes en bosques y pastizales del Iberá

“…Keating (1982) ya describió la presencia de drusas y rafidios en el género Ludwigia, incluyendo esta especie en su análisis, donde además se destaca la presencia de rafidios en células dispuestas horizontalmente en el mesofilo. Altamirano et al (2018) reconocen que en general en las especies terrestres el tamaño promedio de los cristales es menor que en especies que habitan ambientes acuáticos o anegados (12 y 80 μm, respectivamente). Este autor menciona en L. peploides que el tamaño promedio de las drusas es 45 µm y los rafidios 210 µm, siendo similar a los tamaños encontrados en la especie L. peruviana aquí estudiada.…”