Rhubarb’s Toxic Leaves

There’s an obvious explanation why rhubarb didn’t catch on quickly as a food: its leaves are somewhat toxic, perhaps leading would-be connoisseurs to think that rhubarb’s stalks were dangerous as well. Rhubarb leaves contain oxalic acid. When large amounts of oxalic acid are ingested, it can lead to kidney failure and death. But that would take some real effort; a lethal dose requires ingesting around 11 pounds of sour, unpalatable rhubarb leaves.