sheep's sorrel

much smaller and more compact than common sorrel, sheep's sorrel grows on grassy and heathy places often on bare patches with acid soils. Sorrel is supposed to be derived from the old french word surele meaning sour; the leaves contain calcium oxalate which can be poisonous in excess. Of interest (to me) sorrel was used as a herbal remedy for kidney and bladder problems. Most kidney stones are made of calcium oxalate and one might think that eating sorrel might well have made them worse.