Fruit – Definition, Types, Example | Biology Ideas

About Fruit

Fruits are a characteristic of flowering plants.

As soon as pollen and fertilization occur, the ovary of a plant becomes a fruit and the ovules become a seed.

The main purpose of fruits is to protect the seeds during development.

The fruit primarily consists of two parts,

  1. Pericarp – Wall of the fruit.
  2. Seed – Inner part of Fruit.

The pericarp has three layers,

  1. Epicarp: This is the outermost layer of the pericarp that forms the skin.
  2. Mesocarp: It is the thick, fleshy, and juicy or fibrous middle layer of the pericarp.
  3. Endocarp: It is the innermost layer of the pericarp.

Read more on Britannica…

Types of Fruits

Depending on the number of eggs and the number of flowers involved, the fruit is divided into three categories,

Simple Fruits – In this case, only one fruit develops from a monocarpellary or syncarpous ovary of a flower with or without accessory parts. e.g. Mango, Walnut, Plum

Aggregate Fruits – An aggregate fruit is a collection of simple fruitlet developed from an apocarpous pistil of a flower. The fruits are borne by a common stalk. e.g. Custard apple, Grapes.

Multiple Fruits / Composite Fruits – These fruits develop from a number of flowers of an entire inflorescence. e.g. Fig, pineapple

Simple Fruit

These fruits develop from a single ovary of a monocarpellary or syncarpous gynoecium of a single flower with or without accessory parts.

The simple fruit on the basis of the nature of the pericarp is further classified into two categories,

  1. Dry fruits
  2. Fleshy fruits
  3. Dry Fruits

Dry Fruit

The pericarp of these fruits becomes dry, thin, thick, leathery, hard, or papery at maturity.

It cannot be distinguished into distinct layers. These are further subdivided into,

  1. Dehiscent fruits – These fruits dehisce or split open when they mature.
  2. Indehiscent fruits – These fruits do not split open on maturity.

Dehiscent Dry Fruits

Legume

pea
  • This is a simple dry, dehiscent, one chambered and many-seeded fruit.
  • It develops from a monocarpellary, upper, unilocular uterus with two alternating placement lines. The legumes are pulled through the spinal and ventral muscles.
  • e.g. Pea

Follicle

  • This is a simple dry, dehiscent, one chambered and many-seeded fruit.
  • It is found in the monocarpellary, superior, unilocular ovary.
  • It dehisces, however, by only one suture; especially ventral.
  • e.g. Delphinium

Capsule

  • This is a simple dry, dehiscent, uni or multilocular, and many-seeded fruit.
  • It is developed from multicarpellary, superior ovary.
  • The capsule is a common name for all dehiscent fruits developed from the syncarpous ovary.
  • e.g. Cotton, Lady’s finger, Datura, Papaver, Eucalyptus

Indehiscent Dry Fruits

Achene

Mirabilis fruit,achene
  • This is a simple dry, indehiscent, unilocular, and one-seeded fruit.
  • It is developed from a monocarpellary superior ovary.
  • The pericarp of this fruit remains without a seed coat.
  • Pericarp may be hard or leathery.
  • e.g. Mirabilis

Cypsela

  • This is a simple, dry, indehiscent, unilocular, and one-seeded fruit.
  • It is developed from carpellary, syncarpous, and inferior ovary.
  • The pericarp of the fruit is hard and free from the seed-coat.
  • A persistent calyx crown adheres to the fruit with scales or hairs present.
  • e.g. Sunflower, Tridax.
Caryopsis
Caryopsis, maize
  • This is a simple dry, indehiscent, unilocular, and one-seeded fruit.
  • It is developed from a monocarpellary superior ovary.
  • The pericarp of this fruit met the seed coat.
  • e.g. Wheat, Maize

Fleshy Fruits

In these fruits, the fruit wall or pericarp is large and fleshy.

They are indehiscent.

The seeds are liberated after decomposition of pericarp or consumption by animals.

Drupe

mango, drupe fruit, drup type
  • This is a simple, fleshy, and indehiscent fruit.
  • It develops from the monocarpellary or syncarpous and superior ovary.
  • The pericarp is divided into the epicarp (outer skin), mesocarp (fleshy/fibrous flesh), and the hard and rocky endocarp. Therefore drupe is also called stone fruit.
  • Usually, drupe is one-seeded.
  • E.g. Mango, Coconut.

Berry

  • This is a simple, juicy, indehiscent fruit with many seeds.
  • It grows normally from the upper syncarpous uterus, with the axil or parietal Placentation. Here the outer layer epicarp forms the skin of the fruit were as mesocarp and endocarp fused together forming the pulp of the fruit.
  • E.g Tomato, Brinjal.

Hesperidium

Hesperidium, lemon
  • This is a simple, fleshy, indehiscent, and many-seeded fruit.
  • It develops usually from a syncarpous, superior ovary with axil placentation.
  • Here the endocarp projects inwards, forming distinct chambers and unicellular, juicy, glandular hairs from the endocarp extend into chambers. The epicarp and mesocarp fused together, form the loose or tight skin(rind) of the fruit.
  • Many oil glands are present in the epicarp.
  • e.g. Orange, Lemon.

Aggregate Fruits

Combined fruit is a collection of simple fruits that grow from apocarpous pistil (free carpet) of flowers.

An aggregate of simple fruits borne by a single flower is otherwise known as an ‘etaerio’.

Types of etaerios,

Etaerio of berries – E.g. Annona squamosa, A. Reticulata, Artabotrys
Etaerio of achenes – E.g. Clematis, Strawberry, lotus
Etaerio of follicles – E.g. Calotropis, Vinca, Michelia

Etaerio of Berries

  • These fruits are commonly found in the family Annonaceae.
  • In Artabotrys(Hirva Chapa) and Polyalthia (Ashok) the individual berries are free from one another while in Anona squamosal (custard apple) and Anona reticulate (Ramphal) the berries become fleshy and are crowed on thick thalamus and form a complex single fruit.
  • The common rind of the fruit is formed by the fusion of apices of individual berries.

Etaerio of Achenes

  • In this aggregate fruit, each fruit is an achene.
  • In Clematis each achene shows the presence of persistent feathery style with it.
  • In strawberry, the thalamus is fleshy and we can find small achenes on its surface.
  • In the lotus, the thalamus becomes spongy and some achenes are embedded in it.

Etaerio of Follicles

  • In this fruit, each fruitlet is a follicle.
  • They are borne by the enlarged thalamus.
  • There are two follicles in Calotropis and Vinca and numerous in Michelia (Sonchapha).

Composite / Multiple Fruits

A multiple or composite fruit is that which develops from all the flowers of an entire inflorescence.

Generally, all parts of the inflorescence are involved in fruit formation.

In Morus alba (Mulberry) develops a sorosis from catkin inflorescence.

Sorosis

Sorosis, jackfruit
  • In Artocarpus integrifolia (Jackfruit) having spike inflorescence, the flowers are arranged on thick club-shaped rachis.
  • Along with the fertile fruit, tepals become juicy, bracts also become more or less juicy chaffs, while the rachis becomes fleshy and massive.
  • The tough rind of the fruit is formed by the fusion of apices of flowers while the spines on the rind represent the stigmas of the carpels.
  • The seeds and juicy perianth are the edible parts of fruits.
  • In Ananas comosus(Pineapple) the axis of spike inflorescence becomes fleshy by hypertrophy and envelopes the flowers almost completely except the tips of floral bracts.
  • Each polygonal area on the surface of the fruit represents a flower.
  • Seeds are generally not formed.
  • The axis of inflorescence grows above the flowers to form the crown of leaves.
  • The edible part of this fruit includes rachis, perianth, and bracts.

Syconus

  • This fruit is formed from the entire hypanthium inflorescence.
  • In Ficus (Fig) the hollow pyriform receptacle of hypanthium enclosing female flowers at the base becomes fleshy.
  • The female flowers produced tiny achenes.
  • The receptacle has an ostiole at the apex which is surrounded by scales.
  • Fleshy receptacle forms edible part of the fruit.

References

  1. https://www.biologydiscussion.com/plants/fruit-and-its-types-explained-with-examples/6398
  2. https://www.britannica.com/science/fruit-plant-reproductive-body
  3. https://www.biologyonline.com/dictionary/simple-fruit
  4. https://study.com/academy/lesson/fruit-definition-types-benefits-examples.html
  5. https://byjus.com/biology/fruit-formation-parts-types/

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