Apocarpous

The stigma, style, and ovary are the three main structures of the gynoecium, carpel, or pistil. It is the female reproductive portion of the flower that carries the female gametes or ovules within an ovary. The female reproductive component, as well as other sections, are supported by the pedicle or thalamus, which is located near the gynoecium base.

The gynoecium (sometimes spelt gynaeceum) or pistil is the flower’s central or topmost whorl, terminating in the thalamus. One or more carpels or megasporophylls make up the structure.

The pistil is called simple or monocarpellary when there is just one carpel, which is not particularly common but is seen in the major Leguminosae and Gramineae families.

CARPELS 

The carpel is the flower’s fourth whorl, which is found in the centre. The carpels are where the pistil, the flower’s female reproductive part, is kept. In the ovary, the egg or ovule is present. After fertilization, the ovary may transform into fruit to preserve the seed. A vertical structure called the style supports the stigma at the apex of the ovary. Pollens that have been disseminated adhere to the stigma and move along the style to the ovary. 

PISTIL

The pistil is a flower’s female reproductive organ. The pistil is made up of a swollen base, the ovary, which houses the prospective seeds, or ovules; a stalk, or style, which emerges from the ovary; and the stigma is a pollen-receptive point that can be formed differently and is sticky. Compatible pollen grains land on the stigma, germinate and form a pollen tube in the process of pollination. The pollen tube passes through to the style tissue, discharging sperm for the ovary’s ovules to fertilize. Pistils are the parts of the gynoecium.

Pollen–Pistil Interaction

When flower pollination fails to result in successful fertilization, the pistil of the flower must recognize pollen from the same species. As a result, it’s critical to fully comprehend the interplay between pollen grains and the flower’s stigma. When compatible pollen is accepted by a flower’s pistil, the fertilization process continues, and incompatible pollen is rejected. Because of long-term pollen-pistil interaction and compounds generated by pollen, a pistil is capable of recognizing its pollen.

 Pollen-Pistil Interaction Events Follow these steps:

• The initial occurrence of pollen pistil interaction is real pollen landing on a suitable pistil.
• Pollen tubes are formed during pollen germination, allowing pollen grains to discharge their contents.
• Pollen tube develops into the ovary through the style of the pistil.
• Male gametes are inserted into the ovule and then into the synergid.

PARTS OF PISTIL

Stigma

It is the highest component of the female reproductive unit of the flower. The stigma is the part of the pistil head that is exposed to the air or the environment. The stigma’s surface can be sticky, hairy, smooth, rough, and so on. It may easily swallow the pollen grains of the male producing system, or androecium, due to its viscous nature.

The pollen grains are attached to the stigma through a platform. As a result, it is critical for pollination. Stigma comes in a variety of morphologies, including simple, lobed, feathery, funnel-shaped, and branching.

The stigma is made up of stigmatic tissues and single-layered elongated papillary cells. The stigmatic papillae, or elongated papillary cells, serve as a receptor for pollen grains.

As a result, it accomplishes the following tasks:

• Adhesion of pollen
• Pollen grain recognition
• Pollen grain germination is a process in which pollen grains germinate.
• Fertilization has started.
• Prevents pollen grains from many plant species from entering.

Style

It’s a stalk-like, filamentous structure that connects the stigma and the ovary. When pollen lands on the stigma, it begins to migrate down through the style structure. The ovary, or basal whorl, is the source of a style.

The gynobasic style is derived from the ovary’s central basis. It can also appear at a right angle to an ovary axis. Stylopodium style is a type of blossom that seems somewhat inflated and is found mostly in Umbelliferae family members.

Ovary

It is the most important portion of the gynoecium since it is where the female gametes or ovules are produced. If a gynoecium doesn’t have an ovary, it’s either sterile or parthenogenic. To begin fertilization, a pollen particle travels from the style to the ovary and combines with the ovules or megasporangia.

The megasporangia that carry the megaspores are encased and protected by it. Through the placental wall, the ovary also gives nutrients to the growing ovule.

An ovary is classified into the following categories based on the number of chambers or locules:

• Unilocular ovary: It is made up of only one chamber. Pea is a good example
• Bilocular ovary: It is made up of two locules. Petunia is a good example.
• Trilocular ovary: It is made up of three locules. Asphodelus is a good example.
• Tetra ocular ovary: It is divided into four compartments. Osmium is a good example.
• Penta ocular ovary: There are five locules in all. Shoe-flower is a good example.

Functions of Pistil

• The female reproductive component of a flower is another purpose and importance of the pistil.
• Pollen is collected and pollination is aided by it.
• It also plays a role in the germination of pollen grains.
• It also helps pollinate flowers by transferring pollen grains.
• The pistil contains the stigma, which has a sticky tip and is crucial for pollen grain germination.
• It aids in the development of the ovule.

CONCLUSION

The stigma, style, and ovary are the three primary components of the pistil which is a female reproductive part of a flower. The pistil’s primary role is to generate a seed-bearing fruit. The pistil must first be pollinated before it may begin the reproductive cycle. Pollen is transmitted from the anther to the stigma during pollination. The fertilization process can begin after pollen or the male gamete has landed on the stigma. When the male gametes are delivered down the style, fertilization will commence. When male gametes reach the ovary, they can fertilize it, causing the ovary to grow into ovules or female gametes.