If your culinary skills aren’t up to speed, rhubarb is a vegetable with bright ruby leaf stalks similar to celery that’s mostly used in jams, pies, and other desserts. The key is only to eat the stalks. The plant’s leaves contain a chemical called oxalic acid, which is used in bleach and rust removal, according to the U.S. National Library of Medicine. Eating rhubarb leaves induces a slew of bad side effects like burning in your mouth and throat, nausea, vomiting, convulsions—even death. Cooking doesn’t break down these harmful compounds, either.