Pistil and Megasporangium: Definition, Structure, Types

Edited By Irshad Anwar | Updated on Jul 02, 2025 07:11 PM IST

The female reproductive part of the flower is called the pistil. It has components such as stigma, style, and ovary. Pollen is received on the stigma after pollination. The style helps to guide the pollen to the ovary. The megasporangium, also known as the ovule, contains the female gametophyte (embryo sac).

This Story also Contains

The Pistil
Function of the Pistil
Types of Pistils
Megasporangium (Ovule)
Function of Megasporangium (Ovule):
Types of Ovule
MCQs on Pistil And Megasporangium

Pistil and Megasporangium: Definition, Structure, Types

The ovule contains the megaspore mother cell and produces 4 megaspores by the process of meiosis. Out of the 4 megaspores, only one leads to the formation of the embryo sac. Both pistil and megasporangium facilitate sexual reproduction by aiding gamete formation, fertilisation, and eventually, seed formation. Pistil and Megasporangium are important topics in the field of biology.

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.

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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-

Simple Pistil	Compound Pistil
A pistil containing a single carpel or a single unit of fused carpels is usually found in flowers with a single ovary.	If two or more carpels unite, a compound pistil forms with an ovary that contains more than one chamber. This corresponds to the fact that there may be more than one loculus or compartment for ovules.
The simple pistil has one chamber for ovules.	The compound pistil has more than one chamber, each of which may have ovules.

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:

Orthotropous ovule	Ovule is straight. The micropyle, chalaza, and funicle are all in a straight line. Eg.- Cycas
Anatropous ovule	The ovule body is inverted. Because of being inverted, the micropyle is close to the funicle. Eg.- most common type, seen in 82% of angiosperms
Campylotropous ovule	Ovule is curved or bent. Being bent, the micropyle and chalaza are out of alignment. Eg.- Members of Cruciferae
Amphitropous	Ovule as well as the embryo sac is curved like a horseshoe-shaped magnet. Eg - Lemna, Poppy, Alisama
Circinotropous	The ovule turns at more than 360° angle and thus funicle becomes coiled around the ovule . Eg- Opuntia,

Based on the number of integuments:

Unitegmic	Single integument. Seen in gymnosperms, members of gamopetalae.
Bitegmic	Two integuments. Seen in members of polypetalae, monocots
Ategmic	No Integument Seen in Santalum, Loranthus

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.

Read more:

Pollen-Pistil Interaction & Outbreeding Devices	Artificial Hybridisation in Plants - Emasculation and Bagging
Self incompatibility	Angiosperm - Life Cycleof a Flowering Plant
Megasporogenesis	Parts Of A Seed

Frequently Asked Questions (FAQs)

1. What are the parts of a pistil and their functions?

A whole pistil is comprised of three major parts: stigma, style, and ovary. The stigma is the topmost part that captures pollen grains. The style is the stalk that connects the stigma to the ovary through which the pollen tubes grow to reach the ovary. The ovary contains the ovules; upon fertilisation, the ovules develop into seeds.

2. How does the megasporangium develop into an embryo sac?

Meiosis inside a megasporangium—a type of ovule—results in four megaspores. One megaspore will undergo mitotic divisions developing into the embryo sac, otherwise known as the female gametophyte. This includes the egg cell, which develops into an embryo upon fertilisation with sperm cells.

3. What is the difference between a simple pistil and a compound pistil?

A simple pistil is unilocular. While a compound pistil is formed by more than one but fused carpels, resulting in an ovary with multiple chambers, simple pistils likely have only one to the ovary; compound pistils may have as many as several ovules per ovary chamber.

4. What is the role of the pistil in pollination and fertilisation?

The most important part of a plant involved in the process of pollination and fertilisation is the pistil. This part holds and retains pollen grains. From here, because of the process of pollination, the pollen tubes grow and develop down through the style into the ovary, carrying with them the sperm cells. Inside the ovary, these sperm cells fertilise the ovules to finally produce seeds.

5. What are the common types of ovules based on their position?

The common types of ovules concerning their position are:

Anatropous ovule: Inverted ovule; the micropyle is directed towards the placenta.
Orthotropous ovule: Upright ovule; micropyle, chalaza and funiculus are in a straight line.
Campylotropous ovule: The Ovule is curved; the micropyle and chalaza are not in a straight line.
Amphitropous ovule: The ovule partially becomes inverted and curved with both ends of the ovule approaching each other.
Circinotropous ovule: It is an ovule that does a complete turn of 360 degrees.

6. What is a pistil and why is it important in flowering plants?

A pistil is the female reproductive structure of a flower. It's important because it contains the ovary where seeds develop after fertilization. The pistil typically consists of the stigma (which receives pollen), the style (a tube-like structure), and the ovary (containing ovules). Understanding the pistil is crucial for comprehending plant reproduction and seed formation.

7. What is double fertilization and how does it relate to the pistil and megasporangium?

Double fertilization is a unique process in flowering plants where two sperm cells from the pollen participate in fertilization. One sperm fertilizes the egg cell to form the zygote, while the other fuses with two polar nuclei to form the endosperm. This process occurs within the embryo sac, which develops from the megasporangium in the ovule of the pistil.

8. What is apomixis and how does it relate to the megasporangium?

Apomixis is a form of asexual reproduction in plants where seeds are produced without fertilization. In apomictic plants, the megasporangium may develop an embryo sac and embryo without meiosis or fertilization. This process bypasses the usual sexual reproduction pathway but still involves structures within the pistil.

9. How does the structure of the megasporangium change during seed development?

As seed development progresses, the megasporangium (nucellus) typically degenerates. Its nutrients are often absorbed by the developing embryo and endosperm. In some plants, part of the nucellus may persist as a nutritive tissue called perisperm. The ovule's integuments develop into the seed coat, protecting the embryo and nutritive tissues.

10. How do environmental factors affect pistil and megasporangium development?

Environmental factors like temperature, light, and water availability can significantly impact pistil and megasporangium development. Extreme temperatures can disrupt meiosis in the megasporangium or affect pollen tube growth. Drought stress can lead to pistil abortion. Understanding these effects is crucial for predicting plant reproductive success under changing environmental conditions.

11. Can you explain what a megasporangium is in flowering plants?

A megasporangium is a specialized structure within the ovule of a flower where megaspores are produced through meiosis. In flowering plants, the megasporangium is also called the nucellus. It's crucial for the formation of the female gametophyte (embryo sac) and ultimately, seed development.

12. How does the megasporangium contribute to plant reproduction?

The megasporangium produces megaspores through meiosis. One of these megaspores develops into the female gametophyte (embryo sac), which contains the egg cell. This process is essential for sexual reproduction in plants, as it prepares the female reproductive structures for fertilization and seed formation.

13. What is the relationship between the pistil and the megasporangium?

The megasporangium is located within the ovule, which is found inside the ovary of the pistil. Thus, the pistil houses and protects the megasporangium. This arrangement ensures that the female reproductive structures are well-protected and positioned to receive pollen for fertilization.

14. How do ovules develop within the pistil?

Ovules develop from specialized tissue in the ovary called the placenta. Each ovule contains a megasporangium (nucellus) surrounded by protective layers called integuments. The megasporangium undergoes meiosis to produce megaspores, one of which develops into the female gametophyte (embryo sac).

15. How does pollen interact with the pistil structures?

When pollen lands on the stigma, it germinates and grows a pollen tube down through the style. This tube carries the male gametes to the ovary. The pollen tube enters the ovule through a small opening called the micropyle, allowing the male gametes to reach the egg cell in the embryo sac for fertilization.

16. How does the structure of a pistil relate to its function?

The pistil's structure is perfectly adapted to its function. The sticky stigma at the top catches pollen grains. The style provides a pathway for pollen tubes to grow down to the ovary. The ovary houses ovules, which develop into seeds after fertilization. This structure facilitates the process of pollination and fertilization, ultimately leading to seed production.

17. What is the significance of the stigma in the pistil?

The stigma is the receptive surface at the top of the pistil. Its significance lies in its ability to catch and retain pollen grains. The stigma often has a sticky or feathery surface to effectively trap pollen. It also provides the necessary environment and chemicals for pollen germination, initiating the fertilization process.

18. What role does the style play in plant reproduction?

The style connects the stigma to the ovary and provides a pathway for the pollen tube to grow. It often contains specialized tissue called transmitting tissue, which nourishes and guides the growing pollen tube. The length and structure of the style can influence pollination success and act as a barrier against incompatible pollen.

19. How do the structures of the pistil protect the megasporangium?

The pistil's structures offer multiple layers of protection for the megasporangium. The ovary walls surround and shield the ovules containing the megasporangia. The style elevates the stigma, helping to prevent water and debris from directly entering the ovary. This protection is crucial for successful reproduction.

20. What is the evolutionary significance of the pistil in flowering plants?

The pistil represents a key evolutionary innovation in flowering plants. It provides protection for ovules, allows for more precise pollen reception, and facilitates complex pollination mechanisms. The enclosed ovary of angiosperms, unlike the exposed ovules of gymnosperms, offers better protection and has allowed for the development of diverse fruit types, aiding in seed dispersal.

21. What is the difference between a simple and compound pistil?

A simple pistil is formed from a single carpel (modified leaf structure), while a compound pistil is made up of two or more fused carpels. Simple pistils are found in flowers like peas, while compound pistils occur in flowers like lilies. The number of carpels can affect the structure of the resulting fruit.

22. What is the difference between superior and inferior ovaries in pistils?

In a superior ovary, the ovary is positioned above the attachment point of other floral parts (sepals, petals, and stamens). In an inferior ovary, the ovary is below the attachment point of other floral parts. This difference affects fruit development and can be an important characteristic for plant classification.

23. How do pistil structures vary among different plant species?

Pistil structures can vary significantly among plant species. Some plants have a single pistil per flower, while others have multiple pistils. The number of carpels forming the pistil can differ. Style length and stigma shape can also vary, often reflecting different pollination strategies. Some plants have fused pistils, forming complex structures called syncarpous gynoecia.

24. How does the concept of carpels relate to pistil structure?

Carpels are the basic units of the pistil, thought to be evolutionarily derived from modified leaves. A pistil can be formed from a single carpel (simple pistil) or multiple fused carpels (compound pistil). The number of carpels often corresponds to the number of locules (chambers) in the ovary and can affect fruit structure.

25. What is the role of plant hormones in pistil and megasporangium development?

Plant hormones play crucial roles in pistil and megasporangium development. Auxins and cytokinins regulate ovule initiation and development. Gibberellins influence flower development and can affect pistil length. Ethylene can regulate female flower development in some species. Hormonal balance is essential for proper reproductive structure formation and function.

26. How does pollination trigger changes in the pistil and megasporangium?

Pollination initiates several changes in the pistil and megasporangium. The stigma and style often wither after successful pollination. In the ovary, successful fertilization triggers seed and fruit development. Hormonal changes initiated by pollination can prevent the flower from receiving more pollen and redirect plant resources to seed development.

27. What is the significance of the micropyle in ovule structure?

The micropyle is a small opening in the ovule's integuments. It's significant because it provides an entry point for the pollen tube to reach the female gametophyte (embryo sac). The micropyle's position can influence the path of pollen tube growth and is often used to classify ovule types (e.g., anatropous, orthotropous).

28. How do pistil structures contribute to self-incompatibility in some plant species?

In self-incompatible species, pistil structures can prevent self-fertilization. The stigma or style may contain proteins that recognize and reject self-pollen, preventing pollen tube growth. In some cases, the style may allow self-pollen tubes to grow but prevent them from reaching the ovary. These mechanisms promote outcrossing and genetic diversity.

29. What is the difference between wet and dry stigmas, and how does this affect pollination?

Wet stigmas have a surface covered with a liquid secretion, while dry stigmas have little or no secretion. Wet stigmas can capture a wider variety of pollen grains but may be more susceptible to pathogens. Dry stigmas often have specialized papillae for pollen capture and may have more specific pollen-stigma interactions. These differences can affect pollination efficiency and specificity.

30. How does ovule position within the ovary affect seed and fruit development?

Ovule position within the ovary can be classified as axile, parietal, free central, or basal. This positioning affects how seeds develop within the fruit and can influence fruit structure. For example, axile placentation often results in fleshy fruits with seeds embedded in the center, while parietal placentation can lead to fruits with seeds attached to the outer walls.

31. What is the role of the funiculus in ovule and seed development?

The funiculus is a stalk-like structure that attaches the ovule to the placenta in the ovary. It provides a connection for nutrient and water transport to the developing ovule and seed. The point where the funiculus attaches to the seed becomes the hilum, a scar visible on many mature seeds. Understanding the funiculus helps explain seed attachment and nutrient flow during development.

32. How do pistil structures contribute to fruit diversity in flowering plants?

Pistil structures greatly influence fruit diversity. The number of carpels and their arrangement affect fruit structure. Ovary position (superior or inferior) influences whether the fruit includes other floral parts. The ovary wall develops into the pericarp, which can differentiate into various layers, contributing to different fruit types (e.g., drupes, berries, capsules).

33. What is parthenocarpy and how does it relate to pistil development?

Parthenocarpy is the development of fruit without fertilization or seed formation. In parthenocarpic fruits, the pistil, particularly the ovary, develops into a fruit without the usual triggers from pollination and fertilization. This can occur naturally in some plants or be induced artificially, often resulting in seedless fruits. Understanding parthenocarpy is important for fruit crop production and plant breeding.

34. How do sympetalous flowers affect pistil structure and function?

In sympetalous flowers, the petals are fused, often forming a tube. This can affect pistil structure and function by creating a more enclosed floral environment. The style may be longer to extend beyond the petal tube. The ovary is often well-protected at the base of the flower. This structure can influence pollination mechanisms and may be adapted for specific pollinators.

35. What is the significance of the transmitting tissue in the pistil?

Transmitting tissue is specialized tissue found in the style and ovary of the pistil. It's significant because it guides and nourishes the growing pollen tube as it moves towards the ovules. This tissue often contains compounds that attract pollen tubes and provides a pathway for their growth. Understanding transmitting tissue helps explain how plants ensure efficient fertilization.

36. How do pistil structures contribute to pollen selection and mate choice in plants?

Pistil structures play a crucial role in pollen selection and mate choice. The stigma can selectively hydrate or reject pollen grains. The style length can favor faster-growing pollen tubes. Transmitting tissue in the style can differentially support pollen tube growth. These mechanisms allow plants to "choose" which pollen is most likely to achieve fertilization, influencing offspring genetics.

37. What is the role of the integuments in ovule and seed development?

Integuments are protective layers surrounding the megasporangium (nucellus) in the ovule. They play several important roles: they form the micropyle, allowing pollen tube entry; they develop into the seed coat after fertilization, protecting the embryo; and they often store nutrients for seed development. Understanding integuments is crucial for comprehending seed structure and development.

38. How does the concept of megasporogenesis relate to the megasporangium?

Megasporogenesis is the process of forming megaspores within the megasporangium. A megaspore mother cell in the megasporangium undergoes meiosis to produce four haploid megaspores. Typically, three degenerate and one survives to form the female gametophyte. This process is crucial for understanding how plants produce female reproductive cells and prepare for sexual reproduction.

39. What is the evolutionary relationship between carpels and megasporophylls?

Carpels, which make up the pistil, are believed to have evolved from megasporophylls, leaf-like structures that bear megasporangia in more primitive plants. In flowering plants, these structures have become highly modified and enclosed, forming the pistil. This evolutionary change provided better protection for ovules and allowed for the development of fruits, representing a major advancement in plant reproduction.

40. How do pistil structures contribute to species isolation and speciation in plants?

Pistil structures can contribute to species isolation and speciation by creating reproductive barriers. Differences in stigma receptivity, style length, or ovule structure can prevent successful fertilization between closely related species. These differences can arise through adaptation to different pollinators or environments, potentially leading to speciation over time.

41. What is the role of the obturator in some pistils?

The obturator is a structure found in some plants, typically as an outgrowth of the placenta near the micropyle of the ovule. It plays a role in guiding the pollen tube from the style to the micropyle, ensuring more efficient fertilization. The presence and structure of the obturator can vary among plant species and is an important consideration in understanding diverse pollination mechanisms.

42. How does ovule curvature (e.g., anatropous, campylotropous) affect fertilization and seed development?

Ovule curvature refers to the orientation of the ovule within the ovary. Anatropous ovules are completely inverted, campylotropous are curved, and orthotropous are straight. These orientations affect the path of the pollen tube and the development of the seed. For example, in anatropous ovules, the micropyle is positioned close to the funiculus, potentially facilitating pollen tube entry. Understanding ovule curvature helps explain seed structure and embryo orientation.

43. What is the significance of the synergid cells in the female gametophyte?

Synergid cells are part of the female gametophyte (embryo sac) that develops from the megaspore in the megasporangium. They play crucial roles in pollen tube guidance and reception. Synergid cells produce chemical signals that attract pollen tubes and undergo programmed cell death upon pollen tube arrival, facilitating sperm cell release. Understanding synergid function is key to comprehending the final stages of plant fertilization.

44. How do pistil structures in wind-pollinated plants differ from those in insect-pollinated plants?

Wind-pollinated plants often have pistils with large, feathery stigmas to catch airborne pollen. Their styles may be longer and more exposed. In contrast, insect-pollinated plants typically have sticky stigmas and may have more enclosed pistil structures. The ovary in wind-pollinated plants often produces fewer ovules. These differences reflect adaptations to different pollination strategies and efficiency requirements.

45. What is the role of the chalaza in ovule and seed structure?

The chalaza is the base of the ovule where the funiculus connects to the integuments and nucellus. It's significant because it's the site where vascular tissues enter the ovule, providing nutrients. In seeds, the chalazal region often becomes specialized for nutrient transfer to the developing embryo. Understanding the chalaza helps explain seed structure and nutrient flow during development.

46. How do polyploid plants differ in their pistil and megasporangium development?

Polyploid plants, having more than two sets of chromosomes, often show differences in pistil and megasporangium