Oxalic acid
The leaves or roots of "Oxalis pes-caprae" are used in some parts of the world as a food, although the high levels of calcium oxalate in the plant may bear some risks. Such risks can be reduced if the plant parts are boiled first. Oxalic acid is toxic in large quantities, a concern in regions such as southern Australia where "Oxalis pes-caprae" grows invasively in enormous quantities and in high densities. Various sources suggest that "oxalis" ingestion causes calcium oxalate kidney stones, but clinical experience and physiological considerations make it unlikely that any realistic intake of "Oxalis" would affect human liability to kidney stones. Accordingly, some Australian references to the hazards of "oxalis" to livestock tend to be dismissive of this risk.