The structure and origin of different fruits are extremely diverse but there are similarities too so that different types of fruits can be classified. A simple fruit is the product of a single pistil whereas a compound fruit is derived from two or more pistils. Both simple and compound fruits may be partly derived from other parts of the flower or from the flower stalk other than the pistil. Such fruits are called accessory fruits. Raspberries and pineapples are compound accessory fruits. Simple fruits may be fleshy or dry.
Simple Fleshy Fruits: One of the major types of simple fleshy fruits is the berry. The term 'berry' applies to pulpy fruits like tomatoes, grapes, blue-berries. Leathery-skinned fleshy fruits are oranges, limes, kumquats, grapefruits etc. Hard-skinned fleshy fruits are cucumbers and melons. The second major type of fleshy fruit is the drupe or stone-fruit like cherries, peaches and olives. Pome is fleshy accessory fruit like apples or pears.
Simple dry fruits: Simple dry fruits are dehiscent or indehiscent. Dehiscent fruits open when mature to release the seeds. Dehiscent fruits remain closed throughout the period of their development. Dehiscent fruits are pea and bean. Indehiscent fruits are butter-cup and buck wheat.
Compound fruits: There are two general types of compound fruits, viz. aggregate and multiple fruits, each of which is the product of two or more pistils in one flower. They are straw-berries, rasp-berries and black-berries.
Multiple fruits: They sometimes look superficially like aggregate fruits, but these are the products of several separate flowers united into one fleshy whole, which they expand upon maturing. Mulberry, pineapple, breadfruit and orange are good examples of multiple fruits.
