Salicylic acid, the active molecule in aspirin and some acne medications, is a hormone in plants that is essential for immunity, but it's a double-edged sword: Too much can cause autoimmunity and stunt growth. In a study published in Nature Communications, researchers at the University of California , Davis, have discovered that plants use a surprising multi-layered system to regulate salicylic acid levels and keep their immune system in check. ...read more read less