Rhubarb

Rhubarb is a perennial plant grown for its thick, edible stalks, which are tart and are cooked with sugar for use in pies, crumbles, jams and sauces, most often paired with strawberries in classic desserts. Although rhubarb is used culinarily as a fruit, it is botanically a vegetable, and only the stalks are eaten; the plant's broad leaves contain high concentrations of oxalic acid and are toxic if consumed in quantity. Rhubarb is especially associated with British, Northern European and North American home cooking, and its tart flavor before cooking requires substantial added sugar to be palatable in most preparations.