Fruit Development

A fruit results from maturation of one or more flowers, and the gynoecium of the flower(s) forms all or part of the fruit.

Inside the ovary/ovaries are one or more ovules where themegagametophyte contains the egg cell. After double fertilization, these ovules will become seeds. The ovules are fertilized in a process that starts with pollination, which involves the movement of pollen from the stamens to the stigma of flowers. After pollination, a tube grows from the pollen through the stigma into the ovary to the ovule and two sperm are transferred from the pollen to the megagametophyte. Within the megagametophyte one of the two sperm unites with the egg, forming a zygote, and the second sperm enters the central cell forming the endosperm mother cell, which completes the double fertilization process. Later the zygote will give rise to the embryo of the seed, and the endosperm mother cell will give rise to endosperm, a nutritive tissue used by the embryo.

As the ovules develop into seeds, the ovary begins to ripen and the ovary wall, the pericarp, may become fleshy (as in berries or drupes), or form a hard outer covering (as in nuts). In some multiseeded fruits, the extent to which the flesh develops is proportional to the number of fertilized ovules. The pericarp is often differentiated into two or three distinct layers called the exocarp (outer layer, also called epicarp), mesocarp (middle layer), and endocarp (inner layer). In some fruits, especially simple fruits derived from an inferior ovary, other parts of the flower (such as the floral tube, including the petals, sepals, and stamens), fuse with the ovary and ripen with it. In other cases, thesepals, petals and/or stamens and style of the flower fall off. When such other floral parts are a significant part of the fruit, it is called an accessory fruit. Since other parts of the flower may contribute to the structure of the fruit, it is important to study flower structure to understand how a particular fruit forms.

There are three general modes of fruit development:

• Apocarpous fruits develop from a single flower having one or more separate carpels, and they are the simplest fruits.
• Syncarpous fruits develop from a single gynoecium having two or more carpels fused together.
• Multiple fruits form from many different flowers.

Plant scientists have grouped fruits into three main groups, simple fruits, aggregate fruits, and composite or multiple fruits. The groupings are not evolutionarily relevant, since many diverse planttaxa may be in the same group, but reflect how the flower organs are arranged and how the fruits develop.  [Source: Wikipedia]

Aggregate fruit

Aggregate fruits form from single flowers that have multiple carpels which are not joined together, i.e. each pistil contains one carpel. Each pistil forms a fruitlet, and collectively the fruitlets are called an etaerio. Four types of aggregate fruits include etaerios of achenes, follicles, drupelets, and berries. Ranunculaceae species, includingClematis and Ranunculus have an etaerio of achenes,Calotropis has an etaerio of follicles, and Rubus species like raspberry, have an etaerio of drupelets. Annona have Etaerio of berries.

The raspberry, whose pistils are termed drupelets because each is like a small drupe attached to the receptacle. In some bramble fruits (such as blackberry) the receptacle is elongated and part of the ripe fruit, making the blackberry an aggregate-accessory fruit. The strawberry is also an aggregate-accessory fruit, only one in which the seeds are contained in achenes. In all these examples, the fruit develops from a single flower with numerous pistils.[Source: Wikipedia]

Multiple fruits

A multiple fruit is one formed from a cluster of flowers (called an inflorescence). Each flower produces a fruit, but these mature into a single mass. Examples are the pineapple, fig, mulberry, osage-orange, and breadfruit.[Source: Wikipedia]

Berries

Berries are another type of fleshy fruit; they are simple fruit created from a single ovary. The ovary may be compound, with several carpels. Type include (examples follow in the table below):

• Pepo – Berries where the skin is hardened, cucurbits
• Hesperidium – Berries with a rind and a juicy interior, like most citrus fruit [Source: Wikipedia]

Aggregate fruit

Aggregate fruit are formed from the merger of different ovaries of a single flower. [Source: Wikipedia]

Accessory fruit

Some or all of the edible part of accessory fruit is not generated by the ovary. [Source: Wikipedia]

Table of fruit examples

Types of fleshy fruits

True berry	Pepo	Hesperidium	Aggregate fruit	Multiple fruit	Accessory fruit
Blackcurrant, Redcurrant, Gooseberry, Tomato, Eggplant Guava, Lucuma, Chili pepper, Pomegranate, Kiwifruit, Grape, Cranberry, Blueberry	Pumpkin, Gourd, Cucumber, Melon	Orange, Lemon, Lime, Grapefruit	Blackberry, Raspberry, Boysenberry	Pineapple, Fig,Mulberry, Hedge apple	Apple, Rose hip, Strawberry

[Source: Wikipedia]