Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12
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Parts of Flower - Essential Parts of Flower: Gynoecium

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Topics

description

  • Gynoecium: Female Reproductive Organ
  1. Female Reproductive unit: Pistil
  2. Carpel
  3. Number of locules
  4. Extension of the condensed internode of the receptacle
  5. Ovary position
  6. Perianth / Androecial position on thalamus

notes

Gynoecium: Female Reproductive Organ

  • The gynoecium represents the female reproductive part of the flower.
  • Gynoecium consists of carpels or pistils or megasporophylls.
  • Gynoecium (carpel) arises as a small papillate outgrowth of meristematic tissue from the growing tip of the floral primordium. It grows actively and soon gets differentiated into ovary, style and stigma. The ovules or megasporangia arise from the placenta.

notes

Female Reproductive unit: Pistil

  • Each pistil has three parts, the stigma, style, and ovary.
  1. Stigma: The stigma serves as a landing platform for pollen grains.
  2. Style: The style is the elongated slender part beneath the stigma.
  3. Ovary: The basal bulged part of the pistil is the ovary. Inside the ovary is the ovarian cavity (locule). The placenta is located inside the ovarian cavity. Arising from the placenta are the megasporangia, commonly called ovules. The number of ovules can differ from one (e.g., wheat, rice, mango) to many (e.g., papaya, watermelon, orchids). 

Pistil

notes

Carpel:

  • A pistil is derived from a carpel. They are components of a gynoecium.
  • Gynoecium is made of one or more carpels.
  • Carpels may be distinct or connate.

Number of carpel:

  1. Unicarpellary (monocarpellary) - Single carpel Example: Fabaceae
  2. Bicarpellary - Two carpels Example: Rubiaceae
  3. Tricarpellary - Three carpels Example: Cucurbitaceae
  4. Tetracarpellary - Four carpels Example: Lamiaceae.
  5. Multicarpellary - Many carpels Example: Nymphaeceae.

Fusion of carpels:

It is an important systematic character. Apocarpous gynoecium is generally thought to be ancestral condition in Angiosperms.

  1. Apocarpous - A pistil contains two or more distinct carpels. Example: Annona.
  2. Syncarpous - A pistil contains two or more carpels which are connate. Example: Citrus, tomato.

    Fusion of carpels

notes

Number of locules:

Ovarybears ovules on a specialized tissue called placenta. A septum is a crosswall or partition of ovary. The walls of ovary and septa form a cavity called locule. Like that tetralocular and pentalocular ovaries are present according to the locule numbers four or five. More than one locule ovaries are called plurilocular.

Locules

notes

Extension of the condensed internode of the receptacle:

  1. Anthophore: The internodal elongation between calyx and corolla. Example: caryophyllaceae (Silene conoidea).

    Anthophore

  2. Androphore: The internodal elongation between the corolla and androecium. Example: Grewia.

    Androphore

  3. Gynophore: The internodal elongation between androecium and gynoecium. Example: Capparis.

    Gynophore

  4. Gynandrophore or Androgynophore: The unified internodal elongation between corolla and androecium and androecium and gynoecium. Example: Gynandropsis.

    Androgynophore

notes

Ovary position:

The position or attachment of ovary relative to the other floral parts. It may be classified into

  1. Superior ovary: It is the ovary with the sepals, petals, and stamens attached at the base of the ovary.
  2. Inferior ovary: It is the ovary with the sepals, petals, and stamens attached at the apex of the ovary.
  3. Half-inferior ovary: It is the ovary with the sepals, petals, and stamens or hypanthium attached near the middle of the ovary.
  • Hypogynous: The term is used for sepals, petals, and stamens attached at the base of a superior ovary. Example: Malvaceae
  • Epihypogynous: The term is used for sepals, petals, and stamens attached at the middle of the ovary (half-inferior). Example: Fabaceae, Rosaceae.
  • Epigynous: The term is used for sepals, petals, and stamens attached at the tip of an inferior ovary. Example: Cucumber, Apple, Asteraceae.
  • Perigynous: The term is used for a hypanthium attached at the base of a superior ovary.
  • Epiperigynous: The term is used for hypanthodium attached at the apex of an inferior ovary.

notes

Perianth / Androecial position on thalamus:

It describes the placement of the perianth and androecium relative to the ovary and to a hypanthium if present.

Perianth / Androecial position on thalamus

Hypanthium (Staminal disk): a fleshy elevated often nectariferous cup-like thalamus.

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