Editing Calcium oxalate (section)

==Occurrence==
Many plants accumulate calcium oxalate as it has been reported in more than 1000 different genera of plants.<ref>{{cite journal|last=Francesci|first=V.R.|author2=Nakata|title=Calcium oxalate in plants: formation and function|journal=Annu Rev Plant Biol|volume=56|year=2005|issue=56|pages=41–71|doi=10.1146/annurev.arplant.56.032604.144106|pmid=15862089}}</ref> The calcium oxalate accumulation is linked to the detoxification of calcium ({{chem2|Ca(2+)}}) in the plant.<ref>{{cite journal|last=Martin|first=G|author2=Matteo Guggiari|author3=Daniel Bravo|author4=Jakob Zopfi|author5=Guillaume Cailleau|author6=Michel Aragno|author7=Daniel Job|author8=Eric Verrecchia|author9=Pilar Junier|title=Fungi, bacteria and soil pH: the oxalate–carbonate pathway as a model for metabolic interaction|journal=Environmental Microbiology|year=2012|volume=14|issue=11|pages=2960–2970|doi=10.1111/j.1462-2920.2012.02862.x|pmid=22928486|url=https://zenodo.org/record/3436719}}{{Dead link|date=February 2022 |bot=InternetArchiveBot |fix-attempted=yes}}</ref> Upon decomposition, the calcium oxalate is oxidised by bacteria, fungi, or wildfire to produce the soil nutrient [[calcium carbonate]].<ref>{{cite journal |last1=Parsons |first1=Robert F. |last2=Attiwill |first2=Peter M. |last3=Uren |first3=Nicholas C. |last4=Kopittke |first4=Peter M. |title=Calcium oxalate and calcium cycling in forest ecosystems |journal=Trees |date=1 April 2022 |volume=36 |issue=2 |pages=531–536 |doi=10.1007/s00468-021-02226-4 |s2cid=239543937}}</ref>

The [[poison]]ous plant dumb cane (''[[Dieffenbachia]]'') contains the substance and on ingestion can prevent speech and be suffocating. It is also found in [[sorrel]], [[rhubarb]] (in large quantities in the leaves), [[cinnamon]], [[turmeric]] and in species of ''[[Oxalis]]'', [[Araceae]], ''[[Arum italicum]]'', [[taro]], [[kiwifruit]], tea leaves, [[agave]]s, Virginia creeper (''[[Parthenocissus quinquefolia]]''), and ''[[Alocasia]]'' and in [[spinach]] in varying amounts. Plants of the genus ''[[Philodendron]]'' contain enough calcium oxalate that consumption of parts of the plant can result in uncomfortable symptoms. Insoluble calcium oxalate crystals are found in plant stems, roots, and leaves and produced in [[idioblast]]s. [[Vanilla]] plants exude calcium oxalates upon harvest of the orchid seed pods and may cause [[contact dermatitis]].

Calcium oxalate crystals are commonly found in [[lichen]]s, where they occur in two mineral forms: weddellite (CaC<sub>2</sub>O<sub>4</sub>·(2+x)H<sub>2</sub>O) and whewellite (CaC<sub>2</sub>O<sub>4</sub>·H<sub>2</sub>O). These crystals can form both on the surface of the lichen as a powdery coating called {{lichengloss|pruina}} and within the internal structures of the lichen [[thallus]]. The type and distribution of these crystals often correlates with environmental conditions: weddellite typically forms in dry environments and can serve as a water source for the lichen, while whewellite is more common in moist habitats. In addition to water regulation, calcium oxalate crystals in lichens serve several protective functions, including shielding against excessive sunlight and potentially helping to neutralize pollutants such as [[sulfur dioxide]]. The formation of these crystals is linked to the lichen's ability to dissolve calcium from rocky [[substrate (biology)|substrates]] through the production of oxalic acid, with the amount of calcium oxalate often correlating with the calcium content of the substrate on which the lichen grows.<ref name="Wilk & Osyczka 2024">{{cite journal |last1=Wilk |first1=Karina |last2=Osyczka |first2=Piotr |title=Crystalline deposit in lichens: Determination of crystals with regard to practical application in standard taxonomic studies |journal=Acta Mycologica |volume=59 |date=2024-11-14 |doi=10.5586/am/193965 |doi-access=free |pages=1–11}}</ref>

Calcium oxalate, as '''‘beerstone’''', is a brownish precipitate that tends to accumulate within vats, barrels, and other containers used in the brewing of beer. If not removed in a cleaning process, beerstone will leave an unsanitary surface that can harbour microorganisms.<ref>{{cite web|url=https://www.howtohomebrewbeers.com/2018/05/beerstone-removal.html|title=What is beerstone (and how to remove it)|access-date=28 May 2018|last=Ryan|first=James|date=27 May 2018}}</ref> Beerstone is composed of calcium and magnesium salts and various organic compounds left over from the brewing process; it promotes the growth of unwanted microorganisms that can adversely affect or even ruin the flavour of a batch of beer.

Calcium oxalate crystals in the urine are the most common constituent of human [[kidney stones]], and calcium oxalate crystal formation is also one of the toxic effects of [[ethylene glycol poisoning]].