Significant Differences between Anther and Stigma: definition, meaning

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

The anther and stigma are two functionally unique yet basic parts of a flower that participate in the reproductive process. The anther is a part of the male reproductive organ, the stamen, and is mainly responsible for the production and release of pollen grains, which possess the male gametes. At the apex of the filament, the anther is an important organ involved in the transfer of pollen to the female structures of the flower or another flower upon pollination.

This Story also Contains

Definition Of Anther And Stigma
What Is An Anther?
Structure Of Anther
What Is A Stigma?
Structure Of Stigma
Differences Between Anther And Stigma

Significant Differences between Anther and Stigma: definition, meaning

Conversely, the stigma belongs to the carpel or pistil, which is the female reproductive organ. At the apex of the style, the stigma is the surface where pollen grains are received. It is usually sticky or feathery to trap pollen efficiently. The pollen grains germinate after reaching the stigma and develop a pollen tube downward through the style to the ovule. Although they are components of the same reproductive process, the anther and the stigma are greatly different in structure, position, and role.

Definition Of Anther And Stigma

Sexual reproduction in plants occurs through reproductive structures, most of which contain both the male and female organs. The anther is a male reproductive organ that produces and liberates the pollen from the plant, while the stigma is part of the pistil and is a female structure that receives the pollen during fertilisation.

These structures are of immense importance to a plant biologist since they form the core of the plant life cycle, notably the reproductive cycle, by being responsible for carrying genetic material and giving rise to seeds. This is used in agriculture, horticulture, and plant breeding since manipulation of these processes will result in better crop yields and varieties of plants.

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What Is An Anther?

An anther is the pollen-producing component of a stamen, or the male reproductive part of a flower. Usually found at the end of a slender stalk known as the filament, the anther is typically bilobed and has pollen sacs (microsporangia) where pollen grains are formed. These pollen grains contain the male gametes (sperm cells) involved in fertilisation. Upon maturity, the anther discharges the pollen, which gets transferred to the stigma of a flower by wind, water, or pollinators, starting the process of pollination.

Structure Of Anther

The anther is one of the most important parts of the stamen, the male reproductive structure of flowering plants. Its job is to generate and discharge pollen grains containing the male gametes that will be used for fertilisation. The anther is commonly bilobed in structure, with each lobe bearing two pollen sacs or microsporangia. These sacs are where microsporogenesis, the production of the pollen grain, takes place. The structure of the anther is discussed below:

Anther is usually bilobed, i.e., having two lobes.
There are two pollen sacs or microsporangia (a total of four for one anther) within each lobe.
The pollen sacs bear and store pollen grains that contain the male gametes.
The internal sterile tissue dividing the pollen sacs is referred to as the connective.
Another is connected to the filament of the stamen, making up the male reproductive unit.
The exterior anther wall consists of several layers that are the epidermis, endothecium, middle layers, and tapetum (nutritive to pollen in development).

Another serves primarily for pollen generation and storage. The mature pollen is released from the pollen sacs and spread, taken then to the stigma, fertilising it in the process.

What Is A Stigma?

A stigma is the uppermost region of the pistil, the flowering plant's female reproductive organ. It is the surface on which pollen grains land during pollination. Sticky or feathery in nature, the stigma is particularly designed to catch and retain pollen efficiently. After compatible pollen has landed on the stigma, it germinates to produce a pollen tube that extends down the style to the ovule for fertilisation. The position and structure of the stigma are essential to facilitate proper reproduction in flowering plants.

Structure Of Stigma

The stigma is a part of the female reproductive organ in angiosperms and plays an essential role in pollination. Located at the top of the pistil, it is the receptive surface for pollen grains. Its form is particularly shaped to trap and retain pollen, most often sticky, feathery, or glandular. When compatible pollen comes in contact with the stigma, it triggers germination and development of the pollen tube, which results in effective fertilisation. Thus, the stigma plays an important role in maintaining that only the appropriate kind of pollen takes part in reproduction.

The stigma is the outermost portion of the pistil (female reproductive structure) within a flower.
It is usually sticky or feathery to efficiently trap and capture pollen grains.
Above the style, it creates the pollination receptive surface.
The stigma surface can be wet (moist) or dry, based on the plant species.
It usually includes specialised cells or secretions that helps in the recognition of compatible pollen and triggering germination.

Differences Between Anther And Stigma

The anther is a part of the male reproductive organ (stamen) and is responsible for producing and releasing pollen grains. The stigma is part of the female reproductive organ (pistil) and serves as the receptive site for pollen during pollination. While the anther helps in pollen dispersal, the stigma makes sure pollen captured and supports its germination.

Aspect	Anther	Stigma
Structural Differences	Two lobes with pollen sacs (microsporangia)	Sticky or feathery surface
Appearance	Often yellow, sac-like structures	Various shapes, often extended from the pistil
Position	Part of the stamen (male reproductive organ)	Part of the pistil (female reproductive organ)
Functional Differences	Pollen production and release	Pollen reception and germination
Reproductive Role	Male reproductive system	Female reproductive system
Additional Functions	Supports the development of male gametophytes	Supports the growth of pollen tubes
Location and Position in the Flower	Attached to the filament within the stamen	Top of the style within the pistil
Position in Flower	Surrounds the pistil	Centrally located in the flower
Developmental Differences	Formation of microsporangia	Formation of stigma primordia
Intermediate Stage	Differentiation of sporogenous tissue	Development of receptive surface
Final Stage	Release of mature pollen grains	Maturation to capture pollen effectively

Other useful Resources

Different Types Of Apomixis in Plants	Difference Between Pollination And Fertilization
Difference between Apomixis and Polyembryony	Differences between Megasporogenesis and Microsporogenesis
Difference Between Self Pollination and Cross-Pollination	Difference between Male Gametophyte and Female Gametophyte

Frequently Asked Questions (FAQs)

1. What is the main function of anther in plants?

The role of the anther in plants is as an organ that produces and liberates pollen grains containing male gametes for fertilisation. This organ makes up the anther, one of the important organs constituting the stamen and, therefore, considered as the male reproductive organ of the flower.

2. How does the stigma aid in plant reproduction?

The stamen offers the avenue for plant reproduction by receiving the pollen grains for pollination. Most significantly, it is sticky or feathery to catch and hold the pollen. Falling on the stigma, the pollen germinates and forms a pollen tube down the style, then enters into the ovary where fertilisation occurs.

3. What are the differences between anther and stigma?

Anther and stigma could be differentiated based on the structure, function and region of the plant.

Structure: The anther is a sac-like structure which contains pollen sacs while the stigma typically is sticky or has a feathery surface.
Function: Anther produces and releases pollen while stigmata receive and germinate it.
Place: So, while the anther is the stamen and the male organ, the stigma is the pistil and the female organ.

4. Can anther and stigma be found in all types of flowers?

Anther and stigma form part of the majority of flowering plants, that is, angiosperm; still, there are some exceptions. Some plants bear unisexual flowers, either male or female reproductive organs but not both in the same plant or flower. Thus, for such plants, only the staminate flowers will have anthers, and only the pistillate flowers of this type will bear stigmas.

5. What role do pollinators play in transferring pollen from anther to stigma?

A pollinator plays a significantly important role in transferring pollen grains from anther to stigma. While they move from one flower to another, the pollen grains get transferred, which supports cross-pollination and hence improves genetic diversity, enhancing plant reproduction.

6. How does the stigma differ from the anther in terms of its role in plant reproduction?

The stigma is the female reproductive part of a flower that receives pollen grains. Unlike the anther, which produces pollen, the stigma's role is to capture and provide a suitable environment for pollen germination, initiating the process of fertilization.

7. Why are anthers considered part of the stamen, while stigmas are part of the pistil?

Anthers are part of the stamen because they are located at the top of the filament, which together form the male reproductive structure. Stigmas, on the other hand, are part of the pistil (along with the style and ovary) which collectively make up the female reproductive structure of the flower.

8. How do the shapes of anthers and stigmas typically differ?

Anthers are usually elongated or oval-shaped structures that split open to release pollen. Stigmas, in contrast, often have a flattened, sticky, or feathery surface to effectively capture pollen grains from the air or from pollinators.

9. What is the significance of the sticky surface of the stigma?

The sticky surface of the stigma is crucial for capturing and retaining pollen grains that come into contact with it. This adhesive quality ensures that pollen grains stay in place long enough to germinate and grow pollen tubes, which are essential for fertilization.

10. How does the position of anthers and stigmas in a flower relate to their functions?

Anthers are typically positioned higher in the flower to facilitate pollen dispersal by wind or pollinators. Stigmas are often centrally located and may be elevated to increase the chances of pollen reception from various sources.

11. How does the structure of the stigma contribute to its function?

The stigma's structure often includes a large surface area with papillae or hair-like projections. This increases the area for pollen capture and provides a suitable environment for pollen germination, with the papillae secreting substances that support pollen tube growth.

12. What is the difference between wet and dry stigmas?

Wet stigmas have a surface covered with a liquid secretion that aids in pollen hydration and germination. Dry stigmas lack this fluid coating and rely on other mechanisms, such as enzymes in the stigma surface, to support pollen germination. The type of stigma can influence pollination strategies and pollen-stigma interactions.

13. How do the cells in anthers and stigmas differ in their specialization?

Cells in anthers are specialized for pollen production through meiosis and mitosis. In contrast, cells in the stigma are adapted for pollen reception and support, with features like papillae (tiny projections) that help trap pollen and provide nutrients for pollen tube growth.

14. How does the timing of anther maturation and stigma receptivity affect plant reproduction?

The timing of anther maturation (when pollen is released) and stigma receptivity (when the stigma is ready to receive pollen) is critical for successful pollination. In some plants, these events are synchronized to promote cross-pollination, while in others, they may occur at different times to prevent self-pollination.

15. How do anthers and stigmas contribute to plant biodiversity?

Anthers and stigmas play crucial roles in plant reproduction, and their diverse structures and functions contribute to the wide variety of pollination mechanisms in flowering plants. This diversity promotes genetic variation and adaptation, ultimately contributing to plant biodiversity.

16. What is the main function of the anther in flowering plants?

The anther is the male reproductive part of a flower that produces and releases pollen grains. Its primary function is to generate and store pollen, which contains the male gametes (sperm cells) necessary for plant reproduction.

17. What is meant by "dehiscence" in relation to anthers?

Dehiscence refers to the process by which anthers split open to release mature pollen grains. This is a crucial step in plant reproduction, allowing pollen to be dispersed and potentially reach the stigma of another flower.

18. What role does the tapetum play in anther development?

The tapetum is a nutritive tissue layer within the anther that plays a crucial role in pollen development. It provides nutrients and enzymes necessary for pollen maturation and the formation of the pollen wall, eventually degenerating as pollen matures.

19. What is the role of the connective tissue in anther structure?

The connective tissue in an anther connects the two lobes of the anther and attaches it to the filament. It provides structural support and may contain vascular tissue that supplies nutrients to the developing pollen grains within the anther.

20. What is the significance of pollen viability in relation to anther function?

Pollen viability refers to the ability of pollen grains to germinate and fertilize ovules. The anther's role in producing and maintaining viable pollen is crucial for successful plant reproduction. Factors like temperature and humidity can affect pollen viability within the anther.

21. How does the structure of the stigma vary among different plant species?

Stigma structure can vary widely among plant species, adapting to different pollination strategies. Some stigmas are feathery for wind pollination, while others may be lobed or branched to increase surface area for pollen capture. The size, shape, and surface characteristics of stigmas can all vary depending on the plant's specific reproductive needs.

22. What is the significance of pollen coat proteins produced in the anther?

Pollen coat proteins, produced in the anther, play important roles in pollen-stigma interactions. They can be involved in pollen hydration, germination, and pollen tube growth. Some of these proteins may also play a role in self-incompatibility mechanisms, preventing self-pollination in certain plant species.

23. How do environmental factors affect anther and stigma function?

Environmental factors like temperature, humidity, and air pollution can significantly impact both anther and stigma function. High temperatures can reduce pollen viability in anthers, while air pollution can interfere with stigma receptivity. Humidity levels can affect pollen release from anthers and pollen hydration on the stigma.

24. What is the difference between introrse and extrorse anther dehiscence?

Introrse anther dehiscence refers to anthers that open towards the center of the flower, while extrorse dehiscence describes anthers that open away from the flower's center. The direction of dehiscence can influence pollen dispersal and the likelihood of self-pollination versus cross-pollination.

25. How do the chemical compositions of anther and stigma surfaces differ?

The anther surface is often covered with a waxy cuticle that helps protect developing pollen grains. In contrast, the stigma surface may be rich in proteins, lipids, and carbohydrates that support pollen adhesion, hydration, and germination. These chemical differences reflect their distinct roles in the reproductive process.

26. What is the role of the style in connecting the stigma to the ovary?

The style is the elongated part of the pistil that connects the stigma to the ovary. It provides a pathway for pollen tubes to grow from the stigma to the ovary, where fertilization occurs. The length and structure of the style can influence the speed and success of pollen tube growth.

27. How do self-incompatibility mechanisms in the stigma affect plant reproduction?

Self-incompatibility mechanisms in the stigma prevent self-fertilization by recognizing and rejecting pollen from the same plant. This promotes genetic diversity by encouraging cross-pollination. These mechanisms can involve complex molecular interactions between pollen and stigma proteins.

28. What is the significance of pollen-stigma recognition in plant reproduction?

Pollen-stigma recognition is crucial for successful fertilization. It involves molecular interactions that determine whether a pollen grain is compatible and can germinate on a particular stigma. This recognition system helps maintain species boundaries and can prevent hybridization between closely related species.

29. How do anthers and stigmas contribute to plant evolution?

Variations in anther and stigma structures can lead to different pollination strategies, affecting gene flow within and between populations. This can drive speciation and adaptation to different environments. The co-evolution of these structures with pollinators has also played a significant role in plant diversity.

30. What is the role of programmed cell death in anther development?

Programmed cell death plays a crucial role in anther development, particularly in the tapetum layer. The timely degeneration of the tapetum is essential for proper pollen maturation and release. Disruptions in this process can lead to male sterility in plants.

31. How do the vascular connections to anthers and stigmas differ?

Anthers typically have a single vascular bundle supplying nutrients through the filament. Stigmas, being part of the pistil, are connected to a more complex vascular system that extends through the style to the ovary. This difference reflects their distinct nutritional needs and functions.

32. What is the importance of anther orientation in relation to pollination?

Anther orientation can significantly affect pollen dispersal and pollination success. Some flowers have anthers that change orientation during development or in response to environmental cues, optimizing pollen release for specific pollinators or environmental conditions.

33. How do stigma size and shape relate to pollination syndromes?

Stigma size and shape often correlate with specific pollination syndromes. For example, wind-pollinated plants often have large, feathery stigmas to catch airborne pollen, while insect-pollinated flowers may have smaller, sticky stigmas adapted to receive pollen from specific pollinators.

34. What role do volatiles produced by anthers play in plant reproduction?

Volatiles produced by anthers can serve as attractants for pollinators, guiding them to the flower. These chemical signals can be species-specific and play a crucial role in plant-pollinator interactions, influencing the efficiency and specificity of pollen transfer.

35. How does the concept of herkogamy relate to anther and stigma positioning?

Herkogamy refers to the spatial separation of anthers and stigmas within a flower. This arrangement can promote cross-pollination by reducing the likelihood of self-pollination. The degree of herkogamy can vary among species and even within individuals, influencing reproductive strategies.

36. What is the significance of anther appendages in some plant species?

Anther appendages, such as awns or spurs, can serve various functions in different plant species. They may aid in pollen dispersal, act as visual or tactile cues for pollinators, or even function in pollen presentation mechanisms that enhance pollination efficiency.

37. How do anthers and stigmas contribute to the phenomenon of heterostyly?

Heterostyly is a floral polymorphism where flowers of the same species have different arrangements of anthers and stigmas. This can involve variations in style length and anther position, promoting cross-pollination between different flower morphs and reducing self-pollination.

38. What is the role of calcium signaling in pollen-stigma interactions?

Calcium signaling plays a crucial role in pollen-stigma interactions. It is involved in pollen grain recognition, hydration, and germination on the stigma surface. Calcium influx in pollen tubes is also essential for their growth through the style towards the ovary.

39. How do anthers and stigmas contribute to plant reproductive isolation?

Differences in anther and stigma structures, along with their biochemical properties, can contribute to reproductive isolation between closely related plant species. This can include mechanical barriers, differences in timing of maturity, or incompatibility at the molecular level, all of which help maintain species boundaries.

40. What is the significance of stigma receptivity period in plant reproduction?

The stigma receptivity period is the time during which the stigma is capable of supporting pollen germination and tube growth. This period is crucial for successful fertilization and can vary greatly among species. Understanding and timing pollination to coincide with peak receptivity is important in both natural ecosystems and agriculture.

41. How do anthers and stigmas adapt to different pollination vectors?

Anthers and stigmas show various adaptations to different pollination vectors. For example, wind-pollinated plants often have exposed anthers and large, feathery stigmas, while insect-pollinated flowers may have anthers and stigmas positioned to facilitate pollen transfer by specific pollinators.

42. What is the role of the anther endothecium in pollen release?

The anther endothecium is a layer of cells beneath the epidermis that plays a crucial role in anther dehiscence. These cells develop fibrous thickenings that contribute to the mechanical forces necessary for anther opening and pollen release.

43. How do stigmatic papillae contribute to pollen selection?

Stigmatic papillae are specialized cells on the stigma surface that can play a role in pollen selection. They may be involved in recognizing compatible pollen, providing a suitable environment for pollen germination, and in some cases, rejecting incompatible pollen through various biochemical mechanisms.

44. What is the significance of protandry and protogyny in relation to anther and stigma maturation?

Protandry (when anthers mature before stigmas) and protogyny (when stigmas mature before anthers) are temporal separation mechanisms that can promote cross-pollination. These strategies affect the timing of pollen release and stigma receptivity, influencing plant mating systems and genetic diversity.

45. How do anthers and stigmas contribute to the phenomenon of flexistyly?

Flexistyly is a form of temporal separation where the position of anthers and stigmas changes over time. This can involve movement of the style or stamens, altering the relative positions of anthers and stigmas throughout the day or during flower development, which can promote cross-pollination and reduce self-pollination.

46. What role do osmolytes play in maintaining pollen viability within the anther?

Osmolytes, such as sugars and certain proteins, play a crucial role in maintaining pollen viability within the anther. They help regulate water content in pollen grains, protecting them from desiccation and maintaining their metabolic functions until they are dispersed.

47. How does the extracellular matrix of the stigma influence pollen-stigma interactions?

The extracellular matrix of the stigma, composed of proteins, lipids, and carbohydrates, plays a vital role in pollen-stigma interactions. It can influence pollen adhesion, hydration, and germination, and may also be involved in pollen recognition and self-incompatibility responses.

48. What is the significance of anther-stigma mimicry in some orchid species?

In some orchid species, parts of the flower may mimic the appearance of anthers or stigmas to attract pollinators. This mimicry can be part of complex deceptive pollination strategies, where the flower tricks insects into attempting to mate with it or lay eggs on it, thereby facilitating pollen transfer.

49. How do anthers and stigmas contribute to the phenomenon of buzz pollination?

Buzz pollination involves the release of pollen from anthers through vibrations caused by visiting insects. In flowers adapted for buzz pollination, anthers often have small pores at the tips, and pollen is only released when the anther is vibrated at a specific frequency. Stigmas in these flowers are often positioned to receive pollen shaken loose by this mechanism.

50. What is the role of the stigmatic exudate in pollen germination?

The stigmatic exudate is a fluid secreted by wet stigmas that plays multiple roles in pollen germination. It provides moisture for pollen hydration, nutrients for pollen tube growth, and can contain molecules involved in pollen-stigma recognition and self-incompatibility responses.

51. How do variations in anther and stigma morphology contribute to plant speciation?

Variations in anther and stigma morphology can lead to reproductive isolation between populations, potentially contributing to speciation. These variations can affect pollinator interactions, pollen transfer efficiency, and the specificity of pollen-stigma recognition, all of which can drive evolutionary divergence.

52. What is the significance of thigmotropic responses in stigmas?

Thigmotropic responses in stigmas refer to touch-sensitive reactions that can occur when pollen grains land on the stigma surface. These responses can include changes in cellular activity or shape that facilitate pollen capture, hydration, and germination, enhancing the efficiency of the fertilization process.

53. How do anthers and stigmas contribute to the maintenance of genetic diversity in plant populations?

Anthers and stigmas play crucial roles in maintaining genetic diversity through their involvement in various reproductive strategies. These can include mechanisms promoting outcrossing (like self-incompatibility or dichogamy), as well as structures that facilitate efficient pollen dispersal and reception, all of which contribute to gene flow and genetic variation within populations.

54. What is the role of the anther filament in pollen dispersal?

The anther filament, which supports the anther, can play an important role in pollen dispersal. In some species, filaments may elongate