FRUITS

FRUITS

Definition and Origin

  • Etymology: The word "fruits" is derived from the Latin word fructus, which means "enjoy".

  • Botanical Definition: Botanically, fruits are referred to as the ripened ovary and technically include the tissue associated with the ovary.

Functions of Fruit

  • Protective Functions:

    • Protect the seeds as they develop.

    • Facilitate seed dispersion.

    • Allow the plant to reproduce next generations.

  • Nutritional Functions:

    • Storing food for the developing embryo inside the fruit.

    • Adaptations promoting photosynthesis that result in the protection and distribution of seeds.

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  • Common Agents of Dispersal: Fruits and seeds can be dispersed through various agents, which are categorized as follows:

    • Zoochory: Dispersal by animals.

    • Epizoochory: Dispersal when seeds are attached to the animal's body.

    • Endozoochory: Dispersal when seeds are eaten and later excreted by animals.

    • Ornithochory: Dispersal by birds.

    • Mammaliochory: Dispersal by mammals.

    • Chiropterochory: Dispersal via bats.

    • Myrmecochory: Dispersal by ants.

    • Anemochory: Wind-mediated dispersal.

    • Hydrochory: Water-mediated dispersal.

    • Autochory: Self-dispersal by the plant itself.

Types of Fruits: True Fruits vs. Accessory Fruits

  • Pericarp: The tissues of the fruit, regardless of their origin.

    • True Fruits: Contain only ovarian tissue, typically referred to simply as fruits.

    • Origin: Primarily from the ovary wall in most cases.

    • Accessory Fruits (False Fruits): Include non-ovarian tissues, often developed from inferior ovaries.

    • Example: Apples have inferior ovaries, where the bulk of the fruit is made up of enlarged bases of sepals and petals, while only the innermost part consists of true fruit derived from carpels.

Structure of the Pericarp and Its Components

  • Pericarp: The entire fruit wall developing from the ovary wall after fertilization, encompassing:

    • Exocarp: Outermost layer, known as the skin of the fruit.

    • Mesocarp: Middle layer, which is often fleshy or edible.

    • Endocarp: Innermost layer, surrounding the seeds, which could be hard, stony, papery, or thin, depending on the fruit type.

    • Examples:

      • Exocarp: Thin skin of a grape, colored outer peel of a mango, hard outer shell of a nut.

      • Mesocarp: Juicy flesh of mango or peach, creamy flesh surrounding the seed of an avocado.

      • Endocarp: Hard stone/pit of a mango, papery membrane in oranges, shell surrounding coconut seed’s endosperm.

    • Latin Prefixes: "EXO" = outside, "MESO" = middle, "ENDO" = inside.

Classification of Fruit Types (Mauseth, 2017)

  • Fruits can be classified based on several criteria, including how they are dispersed and their structure. The classification presented includes:

Fruit Structural Classification

  • Simple Fruits: Derived from a single ovary.

    • Examples: Peach, Plum, Mango.

  • Aggregate Fruits: Derived from a flower having multiple pistils on a common receptacle.

    • Examples: Blackberry, Strawberry.

  • Multiple Fruits: Derived from separate but closely clustered flowers.

    • Examples: Pineapple, Fig, Mulberry.

Types of Fruit by Maturity: Fleshy vs. Dry

  • Fleshy Fruits:

    • Definition: Fruits where the wall becomes soft and fleshy upon maturity.

    • Classifications of Fleshy Fruits:

    • Drupe: One-seeded fruit from a superior ovary with three distinct layers.

      • Examples: Mango, Peach, Plum.

      • Layer Composition:

      • Exocarp (skin), Mesocarp (fleshy), Endocarp (pit).

    • Berry: Formed from a compound ovary, with the entire pericarp being fleshy.

      • Examples: Grape, Banana.

    • Pome: The thalamus is the edible part.

      • Examples: Apple, Pear.

Special Types of Berries

  1. Hesperidium: Berries with a leathery rind and juice-filled locules.

    • Example: Lemon (Citrus lemon).

  2. Pepo: Berries with a relatively hard rind.

    • Examples: Watermelon, Squash.

Dry Fruits: Definition and Types

  • Definition: Fruits whose coat becomes dry at maturity.

  • Two Major Types of Dry Fruits:

    1. Dehiscent Fruits: Open at maturity to shed their seeds.

    • Examples: Legume, Follicle, Capsule, Silique, Silicula.

      • Legume: Splits along both dorsal and ventral sutures.

      • Follicle: Splits along a single suture.

      • Capsule: Develops from several carpels and splits lengthwise.

    1. Indehiscent Fruits: Do not open at maturity, often single-seeded.

    • Examples: Achene, Nut, Samara, Grain, Schizocarp.

      • Achene: Thin fruit wall with one seed.

      • Nut: Thickened wall compared to an achene.

      • Samara: One or two-seeded with part of the wall growing into a wing.

      • Grain: Seed coat fused to the pericarp, also known as Caryopsis.

      • Schizocarp: Splits into mericarps resembling fruits themselves.