Classification of Fruits

Fruits can be classified on a botanical basis and for several operational purposes.

Botanical Classification

Fruits exhibit a variety of apparent differences that may be used for classification. Some fruits are borne on herbaceous plants and others on woody plants. A very common operational way of classifying fruits is according to fruit succulence and texture on maturity and ripening. On this basis there are two basic kinds of fruits-fleshy fruits and dry fruits. However, anatomically, fruits are distinguished by the arrangement of the carpel from which they developed. A carpel is sometimes called the pistil (consisting of a stigma, style, and ovary), the female reproductive structure.

A fruit is mature ovary. The ovary may have one or more carpel. Even though the fruit is a mature ovary, some fruits include other parts of the flower and are called accessory fruits. Combining carpel number, succulence characteristics, and anatomical features, fruits may be classified into three kinds, simple, multiple, or aggregate.

Simple fruits develop from a single carpel or sometimes from the fusing together of several carpel. This group of fruits is very diverse. When mature and ripe, the fruit may be soft and fleshy, dry and woody, or have a papery texture. There are three types of fleshy fruits.

Fleshy Fruits

1. Drupe: A drupe may comprise one to, several carpels. Usually, each carpel contains one seed. The endocarp (inner layer) of the fruit is hard and stony and is usually highly attached to the seed. Examples are cherry (Prunusspp.), olive, coconut (Cocos nucifera), peach (Prunus persica), and plum (Prunus domestica).
2. Berry: A berry is a fruit characterized by an inner pulp that contains a few to several seeds but not pits. It is formed from one or several carpels. Examples are tomato (Lycopersiconesculentum), grape (Vitis spp.), and pepper (Capsicum anuum). If the exocarp (skin) is leathery and contains oils, as in the citrus fruits (e.g., orange (Citrus sinensis), lemon (Citrus lemon), and grapefruit [Citrus paradisi]), the berry is called a hesperidium. Some berries have a rind, as in watermelon (Citrullus vulgaris), cucumber (Cucumis sativus), and pumpkin (Cucurbita pepo). This type of a berry is called a pepo.
3. Pome: A pome is a pitted fruit with a stony interior. The pit usually contains one seed chamber and one seed. This very specialized fruit type develops from the ovary, with most of the fleshy part formed from the receptacle tissue (the enlarged base of the perianth). Pomes are characteristic of one subfamily of the family Rosaceae (rose family). Examples of pomes are apple (Pyrus malus), pear (Pyrus communis), and quince (Cydonia oblonga).
4. Dry fruits: Dry fruits are not juicy or succulent when mature and ripe. When dry, they may split open and discharge their seeds (called dehiscent fruits) or retain their seeds (calledindehiscent fruits).
5. Dehiscent Fruits. A fruit developed from a single carpel may split from only one side at maturity to discharge its seeds. Such a fruit is called a follicle. Examples are columbine (Aquilegia spp.), milkweed (Asclepias spp.), larkspur (Delphinium spp.), and magnolia (Magnolia spp.). Sometimes, the splitting of the ovary occurs along two seams, with seeds borne on only one of the halves of the spilt ovary. Such a fruit is called a legume, example being pea (Pisum sativum), bean (Phaseolus vulgaris), and peanut (Arachis hypogaea). In a third type of dehiscent fruit, called silique or silicle, seeds are attached to central structure, as occurs in radish (Raphanus sativus) and mustard (Brassica campestris). The most common dehiscent simple seeds are discharged when the capsule splits longitudinally. In some species, seeds are discharged when the capsule splits longitudinally. In others, seeds exit through holes near the top of the capsule, such as in lily (Lilum spp.), iris (Iris spp.), and poppy (Papaverspp.).
6. Indehiscent Fruits: Some indehiscent fruits may have a hard pericarp (exocarp + mesocarp + endocarp). This stony fruit wall is cracked in order to reach the seed. Such fruits are called nuts, as found in chestnut (Castanea spp.) and hazelnut (Corylus spp.). Nuts develop from a compound ovary. Sometimes the pericarp of the fruit is thin and the ovaries occur in pairs, as found in dill (Anethum graveolens) and carrot (Daucus carota). This fruit type is called a schizocarp. In maple (Acer spp.), ash (Fraxinus spp.), elm (Ulmus spp.), and other species, the pericarp has a wing and is called a samara. Where the pericarp is not winged but the single seed is attached to the pericarp only at its base, the fruit is called an achene. Achenes are the most common indehiscent fruits. Examples are the buttercup family (Ranuculaceae) and sunflower. In cereal grains (Poaceae or grass family), the seed, unlike in an achene, is fully fused to the pericarp. This fruit type is called a caryopsis or grain.

Other Operational Classifications

Fruits may also be classified according to other operational uses.

1. Temperate fruits or tropical fruits: Temperature fruits are fruits from plants adapted to cool climates, and tropical fruits are produced on plants adapted to warm climates. For example, apple  (Pyrus malus),  peach  {Prunus domestica)  are  temperate  fruits,  whereas  mango (Mangifera indica) and coconut (Cocos nucifera) are tropical fruits.
2. Fruit trees: Tree fruits are fruits borne on trees, such as apple (Pyrus malus) and mango (Mangifera indica).
3. Small fruits: Small fruits are predominantly woody, perennial, dicot angiosperms. They are usually vegetatively propagated and bear small- to moderate-sized fruits on herbs, vines, or shrubs. Examples are grape (Vitis spp.), strawberry (Fragaria spp.), and blackberry (Rubus spp.). Small fruits require training and pruning (removal of parts of the shoot) to control growth and remove old canes (branches) to obtain desired plant shape and high productivity.
4. Bramble fruits: Bramble fruits are non-tree fruits that usually require physical support (such as a trellis) during cultivation. Examples are raspberry (Rubus spp.), blackberry (Rubus spp.), and boysenberry) (Rubus spp.). Bramble fruits also require training and pruning in cultivation.