Rhubarb

Rhubarb is the common name for Rheum rhaponticum and Rheum rhabarbarum, plants grown for their thick leaf stalks. Although not botanically a fruit, rhubarb is eaten like one, cooked with sugar in pies, crumbles, tarts, and preserves, and it is also used in fruit wines. The stalks are sharply tart because of their organic acids. The leaf blades, by contrast, contain high levels of oxalic acid and can cause poisoning if eaten, so only the stalks are used as food.