Rhubarbs are, botanically speaking, vegetables although they were actually classified a fruit in 1947 Customs Court. The reason was that tariffs were lower on fruits than vegetables and rhubarb was traditionally used as a fruit. Best known for associating with strawberries, it became customary to find the two together, especially in pies. Rhubarb is intensely tart and should be tempered by combining it with sweet fruit or sugar. One cup of unsweetened raw rhubarb has only about 20 calories. The roots and leaves should never be eaten, as they are extremely poisonous.