A fruit is referred to as a ripened ovary and a seed belonging to a flowering plant. It is a soft, pulpy part of the plant formed from the ovaries, particularly of the angiosperms. The anatomy of fruit will explain all of the internal structures of fruit in detail, along with their functions. The fruit consists of various layers, namely the pericarp layer, Endo pericardial layer, exocarp, mesocarp, and endocarp. Based on the number of flowers or number of ovaries present and involved in the formation of fruits, these fruits are generally classified into three main anatomical categories. They are simple fruits, aggregate fruits, and multiple fruits.

ANATOMY OF FRUIT OF A FLOWERING PLANT

The anatomy of fruit is known as the internal structure of the fruit. It consists of single or multiple ovaries, pericarp, endocarp, mesocarp, etc. The anatomy of a flower in detail is as follows:

• Pericarp: The pericarp refers to the outer covering of the entire seed. It is subdivided into three layers, the exocarp or epicarp is the outermost layer, the mesocarp is the middle layer, and the endocarp is the innermost layer. The mesocarp is known to surround the seed or the ovary.
• Exocarp: Exocarp is also known as epicarp. It is the outermost layer of the pericarp and is responsible for forming a tough outer skin of a given fruit. In citrus fruits, epicarp is known as flavedo, composed of cellulose material. Flavedo is composed of several cell layers that eventually get thicker on the inside. The layer is usually surrounded by wax and consists of a few stomata. These stomata are closed in many cases when the fruit is ripe. This internal region of the flavedo is particularly rich in pyriform shapes, which are known for containing essential oils.
• Mesocarp: The mesocarp is referred to as the middle layer of the pericarp of fruit, thus existing between the exocarp and endocarp. It is fleshy in its composition, and it is the part usually eaten in a fruit. It is mainly eaten in fruits like mango, peach (where most of the edible part is mesocarp), and tomato. In citrus fruits, the mesocarp is known as pith or albedo. Pith is the inner part of the fruit peel, which is usually removed while consuming the fruits.
• Endocarp: Endocarp is considered the innermost layer of the pericarp. It is known to surround the seeds and protect them. Endocarp can be membranous, as seen in citrus fruits where it is the only part being eaten, or it could be hard, as seen in drupe fruits, particularly in their Pyrenees. For example, peaches, plums, cherries, apricots, etc. An endocarp is a stony part of the layer surrounding the fruits’ kernel in dried fruits or nuts, like walnuts, pecans, etc. This part is thus removed before eating. The endocarp is usually separated into different sections in citrus fruits, also known as segments. These segments are composed of juice vesicles; that is, it contains the fruit’s juice. 

ANATOMICAL CATEGORIES OF FRUITS

The fruits are classified into three main anatomical categories. This classification is based on the number of flowers or the number of ovaries involved in the formation of various fruits. These categories are as follows,

1. Simple fruits: Simple fruits refer to fruits developed from a single ovary present in a single flower. It may contain either one or many seeds. These fruits can be dry or fleshy. Dry fruits are the type of simple fruits in which the pericarp is not tender or succulent; instead, it becomes dry. For example, nuts like almonds, peanuts, etc. On the other hand, fleshy fruits are the ones in which the pericarp is fleshy and thick such as berries (one which is made up of one or more carpels containing either none or more seeds like grapes, banana, etc.), Drupe (one which contains a single carpel and single seed, with thin skin and fleshy mesocarp like mango), and pome (one which is considered as an accessory fleshy fruit formed from a combination of carpels, surrounded by the receptacle, like apple).
2. Aggregate fruits: Aggregate fruits are the type of fruits formed from a single compound flower and contain several ovaries. Thus, it can be said that it contains a collection of simple fruits, also known as fruitless. The common examples of these types of fruits are strawberries, blueberries, etc.
3. Multiple fruits: The fruits formed by the fusion of ovaries of several flowers are referred to as multiple fruits. This fusion often results in the formation of big fruit. Multiple fruits are also known by two other names: composite or false fruits. The common example of this category of fruits are pineapples, mulberries, etc.

CONCLUSION

Biologically, fruits are defined as a ripened ovary of a flowering plant, particularly angiosperm, consisting of several layers. A fruit mainly consists of a pericarp that surrounds the entire fruit. It is subdivided into three distinct layers, the exocarp or epicarp, the outermost layer. The mesocarp is the middle layer, and the endocarp is known as the innermost layer surrounding the seed. Based on the formation of fruits from the number of ovaries, the fruits are anatomically divided into three categories, simple fruits, aggregate fruits, and multiple fruits.