Pistil and Megasporangium: Definition, Structure, Types

The Pistil

Pistil is the female reproductive organ of the flower and helps in receiving the pollen grain, and also helps in the sexual reproduction of the plant.

• The pistil refers to the female reproductive organ of a flower that produces ova or ovules, which, after fertilisation, develop into seeds.

• The pistil consists of three major parts: stigma, style, and ovary. The stigma is the sticky surface that catches the pollen.

• The style connects it to the ovary, while the latter carries the ovules that develop into seeds upon fertilisation.

• Stigma picks up pollen grains, the style gives way to pollen tubes that find their way down to the ovary, and the ovary contains the ovules, which become seeds upon fertilisation.

Also Read:

• Gametophyte

• Events in the Germination of Pollen Grains

• Significant Differences between Anther and Stigma

Function of the Pistil

The pistil is the female reproductive organ of a flower responsible for receiving pollen, guiding it through the style, and facilitating fertilisation in the ovary.

• The stigma, a part of the pistil, receives the pollen grain after pollination.

• The style, a part of the pistil, guides the entry of the pollen grain into the ovary.

• The ovary protects the ovules and helps in fertilisation by encasing the female gametophyte.

• Post-fertilisation events include the maturation of the ovary into the fruits, which help in protection and seed dispersal.

Types of Pistils

Pistils can be simple (formed from one carpel) or compound (formed from two or more fused carpels). The types of pistils are described below-

Megasporangium (Ovule)

The ovule is the structure within the ovary that develops into a seed after fertilisation and contains the female gametophyte.

• The megasporangium is the structure within the ovary where the megaspores develop into female gametophytes. But it is simply known as the ovule.

• An ovule consists of a few parts, like the nucellus, integuments, and the micropyle. The stalk by which the ovule is attached to the wall of the ovary is known as the funiculus.

Function of Megasporangium (Ovule):

The megasporangium produces the megaspore through meiosis and supports the development of the embryo sac, where fertilisation occurs.

• The ovule has the megaspore mother cell, which forms the embryo sac after the completion of the stages of meiosis.

• The embryo sac in the ovule houses the egg cell, which gets fertilised by the male gamete

• Post-fertilisation, the ovule develops into a seed, containing the embryo and nutritional reserve.
  The ovule provides the necessary nutrients and protection to the female gametophyte and also the embryo.

Types of Ovule

The ovule is located in the ovary and develops into a seed after fertilisation and contains the embryo sac, also called the female gametophyte. The different types of ovules are described below-

Based on the relative position of the micropyle:

Based on the number of integuments:

MCQs on Pistil And Megasporangium

Q1. Ovule is morphologically equivalent to:

Option 1: Megaspore

Option 2: Megasporangium

Option 3: Microspore

Option 4: Megasporophyll

Correct answer: (2) Megasporangium.

Explanation:

The ovule is morphologically similar to a megasporangium, which is the sporangium in seed plants that produce megaspores. It consists of the nucellus, which is the tissue where meiosis takes place and results in the formation of a megaspore. This is important for the production of female gametes in plants. After fertilization, the ovule matures into a seed, which is very important in the reproduction and spread of plants.

Hence, the correct answer is Option (2) Megasporangium.

Q2. Gynoecium (pistil) represents

Option 1: Male gametophyte

Option 2: Female gametophyte

Option 3: The female reproductive structure consists of carpels

Option 4: Embryo sac

Correct answer: (3) The female reproductive structure consists of carpels.

Explanation:

The female reproductive organ of a flower is called the gynoecium, sometimes referred to as the pistil. One or more carpels make up this structure. Usually, each carpel consists of three major components:

• The sticky area that collects pollen is called the stigma.

• Style: The tube that joins the ovary and stigma.

• The organ that houses the ovules, which fertilize and grow into seeds, is called the ovary.

Therefore, following pollination and fertilization, the gynoecium—which is composed of carpels—is in charge of creating seeds.

Hence, the correct answer is Option (3) The female reproductive structure consists of carpels.

Q3. In angiospermic plants, generally pistil consists of

Option 1: Stigma, style and ovary

Option 2: Anther and filament

Option 3: Anther and connectives

Option 4: Stigma and anther

Correct answer: 1) Stigma, style and ovary.

Explanation:

Each pistil has three parts the stigma, style and ovary. The stigma serves as a landing platform for pollen grains. The style is the elongated slender part beneath the stigma. 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.

Hence, the correct answer is option 1) Stigma, style and ovary.

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