11th Class Biology Fruits Fruit

Fruit

Category : 11th Class

Formation of fruit : Fruit is defined as fertilized ovary. The ovary develops into fruit. The ovary wall at maturity forms the wall of the fruit, which is known as pericarp. Sometimes, other parts of flower such as tepals, (e.g., Morus), bracts (e.g., Ananas) or thalamus (e.g., Pyrus) are also involved in the formation of fruit and such fruits are called false fruits or pseudocarps.

The fate of various parts of the ovary during the formation of fruits is summarized below :

 

Types of fruits

They are classified into three groups : Simple, aggregate and multiple or compound fruit.

Simple fruits : They are formed from mono-or polycarpellary but syncarpous ovary. They may be dry or fleshy.

(1) Simple dry fruits have thin, hard and dry, pericarp. They are of three kinds :

(i) Dehiscent or Capsular  (ii) Achenial or Indehiscent  (iii) Schizocarpic

(i) Dehiscent fruit : These fruits are dry, many seeded and split open at maturity. They are of following types :

Legume or Pod : It is characteristic of the family leguminosae; developed from monocarpellary unilocular superior ovary with marginal placentation. It can open or dehisces by both ventral and dorsal sutures. e.g., in Cicer arietinum (Gram); Pisum sativum (Pea) and Phaseolus mungo (Black gram).

Follicle : It is very much resembles the legume but on ripening it opens generally along the ventral suture. e.g., Calotropis, Larkspur, etc.

Siliqua : The fruit is developed from bicarpellary, syncarpous and superior ovary which bears ovules on two parietal placenta. The ovary is unilocular but later becomes bilocular due to the development of a false partition wall called replum. It dehisces from the base towards the apex by both the sutures e.g., In Brassica (Mustard) and is characteristic of the family Cruciferae.

Silicula : It is flattened and short in length from siliqua type, found in Iberis (Candytuft) and Capsella bursa (Shepherd’s purse).

Capsule : It is mono or polycarpellary, dry dehiscent, many seeded fruit which developes from a superior or inferior ovary. It dehisces in almost all the ways i.e., longitudinal and transverse, along both the sutures. Majority of capsules show longitudinal-dehiscence which again are of different types :

Loculicidal : Lines of dehiscence appear along the dorsal sutures, e.g., Gossypium herbacium (Cotton) and  Abelmoschus esculentus (Lady’s finger).

Septicidal : Lines of dehiscence appear along the ventral sutures or septations of the ovaries e.g., in Viola (Pansy), Linseed (Linum).

Septifragel : Lines of dehiscence along irregular lines, but the seeds remain attached to the placenta, as in Datura stramonium (Thorn apple).

(ii) Achenial or Indehiscent fruits : These fruits do not burst at maturity but the seeds are liberated only by the decaying of the pericarp. These are of following types :

Achene : It is small, dry one seeded fruit which develops from a superior or inferior monocarpellary ovary. In this type, the pericarp is tough but thin and free from the seed coat, e.g., in Mirabilis (four o’clock plant) and Clematis. Some times achenes occur in a group from apocarpus ovary where carpels are many e.g., Nelumbium (Lotus).

Caryopsis : It is very small, dry and one seeded fruit which develops from a superior monocarpellary ovary. Here the pericarp is closely fused with seed coat. It is the characteristic of family graminae, e.g., Oryza sativa (Paddy), Triticum aestivum (Wheat) and Zea mays (Maize).

Cypsela : It is dry, one seeded fruit which develops from an inferior , bicarpellary ovary. Here the pericarp is free from seed coat but the thalamus is fused with pericarp. The fruit is provided with a crown of hairs at the top called pappus e.g., in Helianthus annuus (Sun flower), Tridax, Cosmos, Sonchus, etc.

Nut or Glans : It is dry, one seeded fruit which develops from a superior, bi or polycarpellary ovary having a hard pericarp, free from seed coat e.g., in Areca catechu (Betalnut), Anacardium occidentale (Cashewnut) and Trapa natans (Water chestnut). Here the thalamus and sometimes the cotyledons of true fruit are also edible.

Samara : It is dry, one or two seeded fruit, develops from a single mono-or bicarpellary ovary. The pericarp is free from testa and produces a wing like outgrowth which helps in the dispersal of seeds e.g., in Hiptage and Elm.

(iii) Schizocarpic or Splitting fruits : These resemble both (achenial) indehiscent fruits as well as capsular fruits having many seeds. However, they break into one seeded segments known as mericarps. By splitting usually the mericarps are indehiscent but in Ricinus (Castor) they are dehiscent. The important schizocarpic fruits are :

Lomentum : It is a dry, many seeded fruits which develops from a monocarpellary, superior, unilocular ovary with marginal placentation.

The fruit arises just like a legume but when ripened it becomes partitioned between seeds into single seeded mericarps e.g., Acacia arabica (gum tree), Mimosa (touch me not) and Dalbergia sisoo (India red wood tree).

Cremocarp : It is a dry fruit, develops from bicarpellary, syncarpous, bilocular ovary. The fruit when mature breaks into single seeded mericarps which remain attached to the top of the central axis called carpophore, e.g., Daucus carota (Carrot); Foeniculum vulgare (fennel).

Regma : It develops from tri-or penta-carpellary superior syncarpous ovary. The locules are many as the carpels known as Cocci (sing. Coccus), attached to carpophore and separate by splitting e.g., Euphorbia, Geranium and Ricinus.

Carcerulus : It is a dry fruit, develops from bi or polycarpellary syncarpous, multilocular superior ovary with axile placentation. Many single seeded, mericarps are formed by splitting and formation of false septa. e.g., Ocimum sanctum (Sacred basil), Althaea rosea.

(2) Simple fleshy fruit :  The fruits are simple, but the pericarp is fleshy and edible. It is differentited into three layers epicarp, mesocarp and endocarp. Fleshy fruits are of following types:

Drupe : It is a fleshy fruit formed from mono-or poly carpellary superior ovary, where one or more ovules may developes into seeds. Here the epicarp is thin and leathery. The mesocarp is thick, fleshy, juicy and edible in Mangifera (Mango) and fibrous in Cocos (Coconut).

The endocarp is hard and stony in both the cases. In Cocos, pericarp is not edible. The portion inner to endocarp is the liquid endosperm which is edible.

Berry : It is usually many seeded fleshy fruit develops from polycarpellary, syncarpous, superior ovary. Rarely it is single seeded as in Borassus (Palm).

Here the epicarp remains as the skin of the fruit. The mesocarp and endocarp are fused together to form the pulp of the fruit. e.g., Brinjal, Tomato, Banana, etc.

Pepo : It is a special type of berry. Here the epicarp and thalamus form the outer ring of the fruit. The mesocarp, endocarp and placentae are fused to form pulp which is edible; seeds are many. Common examples are Cucurbita maxima (Sweet gourd); Cucumis sativa (Cucurbit).

Pome : The fruit develops from inferior, pentacarpel ovary. The fruit is covered by the fleshy thalamus, which is fused with the pericarp and edible. The outer part again encloses the inner stiff and membranous portion enclosing the seeds; common example is Pyrus indica (Apple).

Hesperidium : It is another type of berry; it develops from a polycarpellary, syncarpous, superior ovary with many seeds. Here the outer skin is thick and leathery that represents the epicarp, which contains oil glands. The fibrous portion fused with epicarp is the mesocarp. The endocarp consists of many chambers with juicy glands. Common examples are Citrus medica (Lemon) and Citrus sinensis (Sweet orange).

Balausta : This is many chambered, many seeded fruit developing from a multicarpellary, syncarpous but inferior ovary. The pericarp of balausta is leathery or tough. The carpels are arranged in two rows. Carlyx is persistent. The seeds have succulent seed coat (testa) which form the edible part; e.g., Punica granatum (Pomegranate).

Aggregate fruits : The aggregate fruits are formed from polycarpellary, apocarpous ovary. Each ripened is called fruitlet or etaerio e.g., the lotus, rose fruit and strawberry are a collection of achenes; raspberry, a collection of drupes and custard apple is a collection of berries.

Composite or compound fruits : Multiple fruit develops from entire inflorescence called sorosis or syconus.

Sorosis : Develops from spike or spadix inflorescence e.g., Pineapple, Jackfruit, Mulberry, etc.

Syconus : Develops from hypanthodium inflorescence e.g., Ficus carica. (banyan).

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