Consumption of oxalates (for example, the grazing of animals on oxalate-containing plants such as greasewood), or human consumption of Sorrel may result in kidney disease or even death due to oxalate poisoning. The presence of Oxalobacter formigenes in the gut flora can prevent this.
The charge on oxalate allows it to act as a chelator of various positively charged metal ions.
Much of its other properties resemble oxalic acid.