Fruit (plant structure)

Fruits are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggregate fruits are formed from a single compound flower and contain many ovaries or fruitlets. Examples include raspberries and blackberries. Multiple fruits are formed from the fused ovaries of multiple flowers or inflorescence. The types of fleshy fruits are berries, pomes, and drupes. In berries, the entire pericarp is fleshy but this excludes the exocarp which acts as more as a skin. There are berries that are known as pepo, a type of berry with an inseparable rind, or hesperidium, which has a separable rind. This means that fleshy fruits were not passed on to following generations but that this form of fruit was selected for in different species. This may imply that fleshy fruit is a favorable and beneficial trait because not only does it disperse the seeds, but it also protects them. There is also a variety of dispersal methods that are used by different plants. The origins of these modes of dispersal have been found to be a more recent evolutionary change. Of the methods of dispersal, the plants that use animals have not changed in many ways from the original trait. Due to this, it may be assumed that animal dispersal is an efficient form of dispersal, however there has been no evidence that it increases dispersal distances. Therefore, the question remains of what evolutionary mechanism causes such dramatic diversity. It has been found, however, that simple changes within developmental regulatory genes can cause large alterations within the anatomical structure of the fruit. Even without knowing the mechanism involved in the biodiversity of fruit, it is clear that this diversity is important to the continuation of plant populations. == Anatomy of simple fruits ==

hesperidium that has been opened to show the pulp (juice vesicles) of the endocarp Fruit anatomy is the plant anatomy of the internal structure of fruit. In berries and drupes, the pericarp forms the edible tissue around the seeds. In other fruits such as citrus and stone fruits (Prunus) only some layers of the pericarp are eaten. In accessory fruits, other tissues develop into the edible portion of the fruit instead, for example the receptacle of the flower in strawberries. == Pericarp layers ==

In fleshy fruits, the pericarp is typically made up of three distinct layers: the outer epicarp, the middle mesocarp and the inner endocarp. These layers vary in thickness and texture, and may blend into each other. In a hesperidium like lemon, the epicarp and mesocarp make up the peel; in many berries like melons or cucumbers (pepo), the mesocarp and endocarp make up the flesh. In dry fruits, the layers of the pericarp are usually hard, dry and not clearly distinguishable. Epicarp Epicarp (from , "on" or "upon" + -carp, "fruit") is a botanical term for the outermost layer of the pericarp (or fruit). pigments (carotenoids, chlorophylls, flavonoids), paraffin waxes, steroids and triterpenoids, fatty acids, bitter principles (limonin), and enzymes. In citrus fruits, the flavedo constitutes the peripheral surface of the pericarp. It is composed of several cell layers that become progressively thicker in the internal part; the epidermic layer is covered with wax and contains few stomata, which in many cases are closed when the fruit is ripe. When ripe, the flavedo cells contain carotenoids (mostly xanthophyll) inside chromoplasts, which, in a previous developmental stage, contained chlorophyll. This hormonally controlled progression in development is responsible for the fruit's change of color from green to yellow upon ripening. Citrus flavedo may be scraped off the fruit to create zest. The internal region of the flavedo is rich in multicellular bodies with spherical or pyriform shapes, which are full of essential oils. Mesocarp The mesocarp (from Greek: meso-, "middle" + -carp, "fruit") is the fleshy middle layer of the pericarp of a fruit; it is found between the epicarp and the endocarp. It is usually the part of the fruit that is eaten. For example, the mesocarp makes up most of the edible part of a peach, and a considerable part of a tomato. "Mesocarp" may also refer to any fruit that is fleshy throughout. In a hesperidium, the mesocarp is the inner part of the peel and is commonly removed before eating, as is found in citrus fruit. It is also referred to as albedo or pith. In citron fruit, where the mesocarp is the most prominent part, it is used to produce succade. Endocarp endocarp Endocarp (from Greek: endo-, "inside" + -carp, "fruit") or putamen are botanical terms for the inside layer of the pericarp (or fruit), which directly surrounds the seeds. It may be membranous as in citrus where it is the only part consumed, or thick and hard as in the pyrenas of drupe fruits of the family Rosaceae such as peaches, cherries, plums, and apricots. In nuts, it is the stony layer that surrounds the kernel of pecans, walnuts, etc., and that is removed before consumption. In citrus fruits, the endocarp is separated into sections, which are called segments. These segments are filled with juice vesicles, which contain the juice of the fruit. == Anatomy of grass fruits ==

The grains of grasses are single-seed simple fruits wherein the pericarp (ovary wall) and seed coat are fused into one layer. This type of fruit is called a caryopsis. Examples include cereal grains, such as wheat, barley, and rice. The dead pericarp of dry fruits represents an elaborated layer that is capable of storing active proteins and other substances for increasing survival rate of germinating seeds. == See also ==