Rhubarb

In botanical terms, rhubarb is a vegetable, but we tend to use it more as a fruit in cakes, pies, and dessert sauces. It is, in fact, actually referred to as pie plant. Rhubarb is great in desserts that are topped with meringue because its tart flavor contrasts beautifully with the sweetness of the meringue. Rhubarb leaves are potentially poisonous (in excessive amounts) because their oxalic acid content is high enough that it can interfere with calcium and iron absorption; only the stalks of the plant are used. Rhubarb stalks look something like overgrown red celery. Rhubarb is very tart and is almost always sweetened. It is quite juicy and will actually dissolve if overcooked. Rhubarb is used mostly in pies (sometimes combined with other fruits; strawberry and rhubarb is a common pair) and in cobblers.