Fleshy fruits constitute a group of fruits of which the major characteristic is that the pericarp of the fruit is fleshy, juicy and tender, i.e., the part of the fruit developed from the ovary wall of the flower after fertilization. Fleshy fruits contain a lot of water and are structurally designed to be consumed by animals and hence to disperse the seeds contained within them. The pericarp of fleshy fruits is usually divisible into three distinct layers, i.e., the outer one is known as the exocarp, the middle one is known as the mesocarp, and the inner one is known as the endocarp. The outer layer in most cases is the skin which is the exocarp, the middle one in most cases is the edible and fleshy part which is the mesocarp, and the inner layer can be either hard or soft depending on the fleshy fruit which is the endocarp. The three layers can be consumed in most types of fleshy fruits, but in some types of fruits, only the mesocarp is consumed due to the hardness or texture of either the endocarp or the exocarp.
Fleshy fruits result from the mature ovary of a flower after fertilization. They are simple, aggregate or multiple depending on the development. A single ovary of a single flower forms a single fleshy fruit and examples are Drupes and berries. An aggregate fruit is where there are multiple ovaries that are part of the same flower, a typical example of which is raspberries or strawberries. Aggregation forms in fleshy fruits when a collection of multiple ovules from multiple flowers are contained within an inflorescence, like a pineapple. Even where such differences in growth patterns exist, the general nature of fleshy fruits remains through softening and extensive growth to allow consumption by humans and animals.
The edible, soft character of fleshy fruits serves an important ecological purpose. Fleshy fruits are typically composed of seeds whose dispersal by animals through a process of ingestion and further expulsion, endozoochory, enables them to be viable and begin the propagation of their kind. The edible part of the fruit is a kind of incentive for animals and stimulates them to eat the fruit and then scatter the seeds to distant areas. This common relationship between plants and animals has encouraged many flowering plants to evolutionary success. The attractiveness of succulent fruits with vivid colors, agreeable odors, and sweet or acidic tastes are all adaptations to attract dispersal agents.
Botanists classify fleshy fruits based on the texture of their pericarp and the number of seeds they contain. Drupes, such as mangoes, peaches, and cherries, have a single seed with a hard endocarp, thick pulpy mesocarp, and thin exocarp. Berries, such as fleshy fruits such as tomatoes, grapes, and bananas, often have a soft exocarp, pulpy mesocarp, and soft endocarp with multiple seeds. Hesperidia, such as oranges and lemons, form a berry that is specialized to produce a leathery peel and juicy interior segments. Pomes, such as apples and pears, develop from the lower ovary and contain elements of the ovary tissue and the covering floral tissue to produce a fruit in which the eaten part is not just ovary tissue.
The importance of fleshy fruits cannot be overstated in the environment and, in addition, they have important functions in agriculture, food, economy and human society. Fleshy fruits are part of the central food staples of foods consumed everywhere in human society and are valuable because they are loaded with water content, dietary fiber, vitamins, minerals and antioxidants. The edible fresh parts of the fruit are a vast majority, and next they are packaged as juices, jams, jellies and dried fruit products. Its manufacture is a valuable horticultural and agricultural sector, and it is an area of major economic importance for tropical and temperate countries.
Fruiting in a fleshy fruit is a complex process by the plant requiring complex hormonal and biochemical modifications inside the plant. After fertilization and pollination, the ovary grows and the cells multiply and develop quickly. Auxins, gibberellins and cytokinins are active hormones that contribute to the regulation of fruit development. During the ripening stage of the fruit, starch is hydrolyzed into sugars, chlorophyll is degraded, and pigments such as carotenoids and anthocyanins accumulate, resulting in the characteristic color of fleshy fruits. The texture is also relaxed by enzymatic action that hydrolyzes cell wall components such as cellulose and pectin. All of these render the fruit edible and more attractive, but also communicate palatability to potential seed dispersers.
Among the evolution of plants, fleshy fruit development is a significant innovation. By producing such beautiful and nutritious structures to enclose their seeds, plants afforded more effective seed dispersal mechanisms and facilitated the colonization of a variety of habitats and ecological niches. This reduced the reliance on abiotic mechanisms of dispersal such as water and wind and provided a more controlled and secure mechanism for seed dispersal with the assistance of biotic organisms.
Fleshy fruits may be further referred to as fruit whose pericarp softens, becomes juicy, and is generally edible when bruised, and has an animal-attracting organ more or less exclusively for the purpose of seed dispersal. The size, form, colour, and structure of the fruit Such fruits are highly diverse, yet share certain characteristics due to their fleshy nature and adaptations. They form the backbone of plant reproductive strategies, play a major role in most ecosystems, and are of vital importance to human survival for their dietary, medicinal, and economic uses.
