Oxalate Crystal

Ok. I had to know. What is an oxalate crystal? Why do these two words show up in every discussion of skunk cabbage. What they do is successfully produce a nasty sour taste as well as poisonous condition  in the herbivore's mouth- large deer, or small rabbit, for instance, looking for a green salad after a very icy winter. The oxalate crystals make the muncher's mouth burn fiercely and swell. So it is understandable that any animal who lunches on skunk cabbage will feel the mouth pain before supper. But that's not all.  These raphids, or crystals, are made up of calcium.  Most undesirable is  the oxalate, a  poisonous, crystalline  acid that produces this sour taste  and causes the burning, swelling and choking.  Some scientists suggest that this is the way woody plants get rid of the much needed calcium they must absorb  for growth.  Rhubarb and spinach are two common edible plants that have a significant amount of oxalate crystals. Interestingly, humans who suffer with kidney stones, or oxalate crystals that are excreted painfully in the urine, also are advised to eat a low oxalate diet.