Bilobed Anther

Bilobed Anther

Edited By Irshad Anwar | Updated on Jul 02, 2025 05:21 PM IST

The bilobed anther is an important component of the male reproductive part of flowering plants as it produces and dehisces the pollen grains. This topic is explained under the Class 12 chapter Sexual Reproduction in Flowering Plants of Biology. Questions may appear in competitive exams like NEET about the structure of an anther, diagrammatic representation and related concepts like microsporangia and pollen formation.

This Story also Contains

Definition of Anther
Structure of an Anther
Microsporangia
Bilobed Nature of Anther

Bilobed Anther

Definition of Anther

The anther belongs to the stamen and is the organ for the production and storage of pollen grains in flowering plants. In this light, anthers are concerned with pollen transfer from one flower to another and, in turn, fertilisation in plant reproduction. In this regard, one bilobed anther structure with two distinct lobes, each lobe containing pollen sacs, is quite important in its efficiency for pollen release. This structure allows for maximum dispersal of pollen grains and thus offers a chance for successful pollination and an increase in the genetic diversity of plants.

Structure of an Anther

The structure of the anther is described below-

Anther

Anther and its Parts

The anther is that part of the stamen that bears pollen, and it is usually bilobed with two pollen sacs or microsporangia within each lobe.

Two lobes of Anther

Within an anther, two lobes are connected using a connective tissue; each lobe is further subdivided into two microsporangia.

Epidermis

It is the outer protective layer of the anther that protects the inner tissues from the harsh conditions of the environment.

Endothecium

This layer is just inside the epidermis, which supplies the force for anther dehiscence or opening, hence releasing the pollen.

Middle layers

It consists of a few layers of cells which help in providing structure support and also participate in the maturation of anther.

Tapetum

This is the innermost single layer lining the anther wall that supplies nutrition to the developing pollen grains.

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Microsporangia

Microsporangia are the pollen sacs in the anther, inside which microsporogenesis takes place for the formulation of microspores.

Development of microspores

Microsporogenesis - the process in which a diploid microsporocyte undergoes meiosis to yield haploid microspores.

Bilobed Nature of Anther

By bilobed structure, it means an anther that is divisional into two distinct lobes, wherein each of these lobes contains two microsporangia.

Bilobed Nature of Anther

Importance of bilobed structure in pollen release

The above structure is specifically designed to let the pollen grains disperse from the anther for fertilisation.

Thecae

These anther lobes are further divided into two thecae, which act as the chambers for storing pollen.

Function and significance in pollen storage

The thecae will ensure the pollen is kept safe up to when it would have matured to be dispersed.

Connective Tissue

Connective tissue forms the centre of the anther, joining the two lobes together and containing vascular tissues that feed the anther.

Also Read:

Megasporogenesis	Ovule
Pollination	Abiotic Agents of Pollination
Parts of a Seed	Embryogeny

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Frequently Asked Questions (FAQs)

1. Is anther haploid or diploid?

An anther is diploid (2n) in structure, along with the plant itself.

2. What is the process of cutting down an anther?

Emasculation is the removal of stamens from the female parents' bisexual flowers in order to prevent self-pollination. It is done before the anthers are mature.

3. Does one female flower possess another?

No, an anther is a male gamete-producing body, so unless the flower is not bisexual or male, it lacks an anther.

4. Anthers are important for self-pollination.

Yes, both the anther and the ovary must be present in the same flower, or at least in different flowers of the same plant, to achieve self-pollination.

5. What if we remove the anthers before their dehiscence?

Removing the anthers before they dehisce will result in the death of both the anthers and the pollen within them. It is a practice that is used to prevent self-pollination.

6. What is a bilobed anther?

A bilobed anther is the pollen-producing part of a stamen in flowering plants, consisting of two lobes connected by connective tissue. Each lobe contains two pollen sacs called microsporangia.

7. How does the structure of a bilobed anther contribute to its function?

The bilobed structure maximizes pollen production by providing four separate chambers (two in each lobe) for pollen development. This design also facilitates pollen dispersal, as the lobes can split open easily to release mature pollen grains.

8. What is a theca in relation to a bilobed anther?

A theca is one of the two lobes that make up a bilobed anther. Each theca contains two pollen sacs (microsporangia), where pollen grains develop and mature.

9. How many microsporangia are typically found in a bilobed anther?

A bilobed anther typically contains four microsporangia, with two microsporangia in each lobe (theca).

10. What is the difference between dithecous and monothecous anthers?

Dithecous anthers have two thecae (lobes), which is the typical bilobed structure. Monothecous anthers have only one theca, often due to the loss or non-development of the other theca during evolution.

11. What is the role of calcium in anther dehiscence?

Calcium plays a crucial role in anther dehiscence by regulating the swelling and rupture of the stomium (the region where the anther splits). Changes in calcium concentrations trigger cellular responses that lead to anther opening and pollen release.

12. How do pesticides and environmental pollutants affect bilobed anther function?

Pesticides and pollutants can disrupt anther development, pollen formation, and dehiscence. They may cause male sterility, reduce pollen viability, or alter the timing of pollen release, potentially impacting plant reproduction and ecosystem health.

13. What is the significance of anther orientation in relation to other floral parts?

Anther orientation relative to other floral parts (e.g., petals, stigma) can influence pollination efficiency. It may determine how easily pollinators can access pollen or how effectively wind can disperse pollen in anemophilous species.

14. How do bilobed anthers in ancient plant lineages (e.g., gymnosperms) differ from those in angiosperms?

Gymnosperms typically have simpler reproductive structures compared to angiosperms. Their pollen-producing organs (microsporangia) are often arranged in cone-like structures rather than the complex bilobed anthers found in flowering plants.

15. How do epigenetic factors influence bilobed anther development and function?

Epigenetic factors, such as DNA methylation and histone modifications, can regulate gene expression in anthers. These epigenetic changes can influence anther development, pollen formation, and even traits like male sterility, which are important in plant breeding.

16. How does pollen develop within the microsporangia of a bilobed anther?

Pollen develops through meiosis of microspore mother cells within the microsporangia. This process produces haploid microspores, which then mature into pollen grains through mitosis and cellular differentiation.

17. How does the orientation of anther dehiscence affect pollen dispersal?

The orientation of anther dehiscence can be introrse (facing inward towards the center of the flower), extrorse (facing outward), or latrorse (facing sideways). This orientation affects how easily pollinators can access the pollen and how effectively it can be dispersed by wind or other means.

18. What is the tapetum, and what role does it play in bilobed anthers?

The tapetum is a nutritive tissue layer lining the inner wall of the microsporangia in bilobed anthers. It provides nutrients and enzymes essential for pollen development and may contribute to the formation of the pollen wall.

19. What is anther senescence, and how does it affect pollen viability?

Anther senescence is the aging process of anthers after pollen release. It involves programmed cell death and can affect pollen viability. Understanding this process is crucial for plant breeding and conservation efforts.

20. What is anther culture, and how is it used in plant biotechnology?

Anther culture is a technique used to produce haploid plants by culturing immature anthers or isolated microspores. This method is valuable in plant breeding and genetic research, allowing for the rapid development of homozygous lines.

21. How do bilobed anthers protect developing pollen from environmental stresses?

The structure of bilobed anthers provides some protection for developing pollen. The anther wall, including layers like the epidermis and endothecium, helps shield pollen from UV radiation, dehydration, and some pathogens.

22. What is the function of the connective tissue in a bilobed anther?

The connective tissue joins the two lobes (thecae) of the anther and attaches the anther to the filament. It provides structural support and may contain vascular tissue to supply nutrients to the developing pollen.

23. What is anther versatility, and how does it relate to bilobed anthers?

Anther versatility refers to the ability of an anther to pivot on its filament attachment point. In bilobed anthers, this can allow the anther to swing or rotate, potentially improving pollen dispersal or adapting to specific pollinators.

24. What role do bilobed anthers play in plant taxonomy and classification?

The structure, arrangement, and characteristics of bilobed anthers are important features in plant taxonomy. They can help botanists identify and classify plant species, as anther morphology often varies between different plant families and genera.

25. What is anther-stigma separation, and why is it important in bilobed anthers?

Anther-stigma separation refers to the physical distance between the anthers and the stigma in a flower. In many plants with bilobed anthers, this separation helps prevent self-pollination and promotes outcrossing, increasing genetic diversity.

26. How do environmental factors affect the development of bilobed anthers?

Environmental factors such as temperature, humidity, and light can influence anther development. Extreme conditions may lead to malformed anthers, reduced pollen production, or altered timing of pollen release, potentially affecting plant reproduction.

27. How does the size of bilobed anthers vary among different plant species?

Anther size can vary greatly among species, from tiny anthers in small flowers to large, showy anthers in some ornamental plants. The size often correlates with the overall flower size and pollination strategy of the plant.

28. How do temperature extremes affect the function of bilobed anthers?

High temperatures can cause pollen sterility or premature anther dehiscence, while low temperatures may delay anther development or pollen release. These effects can significantly impact plant reproduction and crop yields.

29. How do symbiotic relationships (e.g., with mycorrhizal fungi) affect bilobed anther development?

Symbiotic relationships, particularly with mycorrhizal fungi, can influence plant nutrition and hormone balance. This, in turn, can affect anther development, pollen production, and overall reproductive success of the plant.

30. What is the significance of anther-stigma interactions in self-pollinating plants with bilobed anthers?

In self-pollinating plants, close anther-stigma interactions are crucial for successful reproduction. The positioning and timing of anther dehiscence relative to stigma receptivity ensure efficient pollen transfer and fertilization within the same flower.

31. What is dehiscence in relation to bilobed anthers?

Dehiscence is the process by which mature anthers split open to release pollen. In bilobed anthers, this typically occurs along a line of weakness in each theca, allowing the pollen to be dispersed.

32. What is the evolutionary significance of the bilobed anther structure?

The bilobed structure evolved as an efficient way to produce and disperse pollen. It allows for increased pollen production in a compact space and facilitates various dispersal mechanisms, contributing to the reproductive success of flowering plants.

33. How do bilobed anthers contribute to cross-pollination in flowering plants?

Bilobed anthers facilitate cross-pollination by producing and releasing pollen that can be transferred to other flowers. Their structure and positioning within the flower often promote pollen pickup by pollinators or dispersal by wind.

34. How do some plants modify their bilobed anthers to prevent self-pollination?

Some plants have evolved mechanisms such as protandry (anthers mature before stigmas) or protogyny (stigmas mature before anthers). Others may have physical barriers or different maturation times for anthers and stigmas within the same flower.

35. How do bilobed anthers in wind-pollinated plants differ from those in insect-pollinated plants?

Wind-pollinated plants often have larger, more exposed bilobed anthers that produce copious amounts of small, light pollen. Insect-pollinated plants typically have smaller anthers with stickier pollen, often positioned to facilitate pollen transfer by specific pollinators.

36. How do hormones influence the development and function of bilobed anthers?

Plant hormones like auxins, gibberellins, and cytokinins play crucial roles in anther development, pollen maturation, and anther dehiscence. Hormonal imbalances can lead to male sterility or other reproductive abnormalities.

37. What is the endothecium, and what is its role in anther dehiscence?

The endothecium is a layer of cells beneath the epidermis of the anther wall. It develops fibrous thickenings that contribute to the mechanical force needed for anther dehiscence, helping to split open the anther and release pollen.

38. How do bilobed anthers in cleistogamous flowers differ from those in chasmogamous flowers?

In cleistogamous (closed, self-pollinating) flowers, bilobed anthers are often smaller and produce less pollen compared to chasmogamous (open, cross-pollinating) flowers. The anthers in cleistogamous flowers may also have modified dehiscence mechanisms to ensure self-pollination.

39. What are some common abnormalities or defects that can occur in bilobed anthers?

Common abnormalities include anther sterility (failure to produce viable pollen), indehiscent anthers (failure to open and release pollen), and malformed anthers due to genetic mutations or environmental stresses.

40. How do bilobed anthers in aquatic plants adapt to their underwater environment?

Aquatic plants may have modified bilobed anthers that release pollen underwater or at the water surface. Some species have anthers that only open above water, while others have pollen adapted for underwater dispersal.

41. What is the significance of anther color in plant reproduction?

Anther color can play a role in attracting pollinators, with some flowers having brightly colored anthers that contrast with the petals. In some cases, anther color may also indicate pollen maturity or viability.

42. How do parasitic plants modify their bilobed anthers compared to non-parasitic plants?

Parasitic plants may have reduced or modified bilobed anthers depending on their level of parasitism. Some holoparasites (complete parasites) may have greatly reduced reproductive structures, while hemiparasites may retain more typical anther structures.

43. What is the relationship between anther size and pollen grain size in bilobed anthers?

Generally, there is a positive correlation between anther size and pollen grain size. Larger anthers tend to produce larger pollen grains, although this can vary depending on the plant's pollination strategy and evolutionary history.

44. How do bilobed anthers in monoecious plants differ from those in dioecious plants?

In monoecious plants (with separate male and female flowers on the same plant), bilobed anthers are found only in male flowers. In dioecious plants (with male and female flowers on separate plants), the anthers in male flowers may be larger or produce more pollen compared to monoecious species.

45. What role do bilobed anthers play in the production of hybrid seeds?

Bilobed anthers are crucial in hybrid seed production. Plant breeders may manipulate anther development or remove anthers (emasculation) in one parent to control pollination and create specific hybrid crosses.

46. What is anther-specific gene expression, and why is it important?

Anther-specific gene expression refers to genes that are primarily or exclusively active in anthers. These genes are crucial for proper anther development, pollen formation, and dehiscence, and are important targets for research in plant reproduction and biotechnology.

47. How do bilobed anthers in self-incompatible plants differ from those in self-compatible plants?

Bilobed anthers in self-incompatible plants may have mechanisms to prevent self-pollen from germinating on the stigma. This can include differences in pollen wall composition or the timing of pollen release relative to stigma receptivity.

48. How do bilobed anthers in carnivorous plants differ from those in non-carnivorous plants?

Carnivorous plants often have modified floral structures, including anthers, to balance their dual needs of attracting pollinators and trapping prey. Their bilobed anthers may be positioned to avoid interference with prey capture mechanisms while still allowing for effective pollination.

49. What is the role of programmed cell death in anther development and function?

Programmed cell death is crucial in anther development, particularly in the tapetum layer. It also plays a role in anther dehiscence, where controlled cell death helps create lines of weakness for pollen release.

50. How do bilobed anthers contribute to pollen allergenicity?

Bilobed anthers produce and release pollen grains that can cause allergic reactions in humans. The structure and dehiscence mechanism of the anthers influence how easily pollen is dispersed into the air, affecting its allergenic potential.

51. What are some current biotechnological applications involving bilobed anthers?

Biotechnological applications include the development of male-sterile plants for hybrid seed production, genetic modification of anther traits for improved crop yields, and the use of anther culture for rapid plant breeding and haploid production.

52. What role do bilobed anthers play in the coevolution of plants and their pollinators?

Bilobed anthers have coevolved with pollinators, developing various adaptations to enhance pollen transfer. These may include specific anther positions, colors, or release mechanisms that match the behavior and morphology of their primary pollinators.

53. What is the relationship between anther wall thickness and pollen viability?

Anther wall thickness can affect pollen viability by influencing the microenvironment within the anther. A thicker wall may provide better protection against environmental stresses but could also impact the efficiency of pollen release during dehiscence.

54. How do bilobed anthers in polyploid plants differ from those in diploid plants?

Polyploid plants often have larger anthers and may produce larger or more numerous pollen grains compared to their diploid counterparts. The increased gene dosage in polyploids can also affect anther development and function.

55. What are the implications of climate change on bilobed anther function and plant reproduction?

Climate change can affect bilobed anther function through altered temperature and precipitation patterns. This may lead to changes in pollen development, viability, and release timing, potentially disrupting plant-pollinator interactions and impacting ecosystem dynamics and crop production.