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UPSC MainsBOTANY-PAPER-I201910 Marks150 Words
Q5.

Draw a well labelled longitudinal sectional view of the structure of capsule of Funaria.

How to Approach

This question requires a detailed, labelled diagram of the Funaria capsule's longitudinal section. The approach should focus on accurately depicting the key structures within the capsule – operculum, peristome teeth, columella, capsule wall, seta, and archesporium. Emphasis should be on clear labelling and proportional representation of these components. A concise understanding of the function of each part will aid in accurate depiction. The answer should be presented as a well-drawn, neat diagram.

Model Answer

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Introduction

Funaria hygrometrica, a common moss, exhibits a distinct sporophytic generation characterized by a capsule borne on a seta. The capsule is the spore-producing structure, crucial for the moss’s reproduction. Understanding its internal anatomy is fundamental to comprehending the life cycle of bryophytes. A longitudinal section reveals a complex arrangement of tissues responsible for spore development and dispersal. This detailed structure facilitates efficient propagation, making Funaria a significant model organism for studying plant reproduction.

Here's a well-labelled longitudinal sectional view of the structure of the capsule of Funaria:

Funaria Capsule Longitudinal Section

Key Structures and their Functions:

1. Capsule Wall

The capsule wall is composed of multiple layers of cells, providing protection and support to the developing spores. It consists of:

  • Exothecium: The outermost layer, often with thickenings.
  • Mesothecium: The middle layer, involved in spore development.
  • Endothecium: The innermost layer, contributing to spore release.

2. Operculum

A lid-like structure covering the mouth of the capsule. It detaches to allow spore dispersal.

3. Peristome Teeth

Highly specialized hygroscopic structures located beneath the operculum. They regulate spore release based on humidity levels. These teeth move in response to changes in moisture, facilitating gradual spore discharge.

4. Columella

A central sterile column of elongated cells that provides support to the developing spores and facilitates their dispersal. It extends from the base of the capsule to just below the operculum.

5. Archesporium

A layer of cells at the base of the capsule that undergoes meiosis to produce spores. It is the initial spore mother cell.

6. Seta

The stalk that supports the capsule, connecting it to the gametophyte. It provides elevation for spore dispersal.

7. Spores

The haploid reproductive cells produced within the capsule. They are released for germination and the development of new gametophytes.

8. Central Strand

A strand of tissue running through the columella, providing structural support and facilitating nutrient transport.

The capsule's structure is intricately adapted for efficient spore dispersal, ensuring the continuation of the Funaria life cycle.

Conclusion

The capsule of <em>Funaria</em> is a remarkably adapted structure for spore production and dispersal. Its layered wall, peristome teeth, and columella all contribute to the successful propagation of this common moss. Understanding the anatomy of the capsule is crucial for comprehending the reproductive strategies of bryophytes and their ecological significance. Further research into the mechanisms regulating spore release could provide insights into plant adaptation and evolution.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

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Additional Resources

Key Definitions

Hygroscopic
Hygroscopic refers to a substance's ability to attract and hold water molecules from the surrounding environment. In the context of Funaria, the peristome teeth are hygroscopic, meaning they move in response to changes in humidity.
Gametophyte
The haploid generation in the life cycle of plants exhibiting alternation of generations, such as mosses. In Funaria, the gametophyte is the dominant, photosynthetic phase.

Key Statistics

Bryophytes, including mosses like Funaria, are estimated to cover approximately 3-5% of the Earth’s land surface.

Source: Raven, P.H., Evert, R.F., & Eichhorn, S.E. (2013). Biology of Plants (8th ed.). W.H. Freeman and Company.

Approximately 12,000 species of mosses have been identified globally, representing a significant portion of bryophyte diversity.

Source: Hill, M.O., & Preston, C.M. (2001). Ecology and biogeography of mosses. CABI Publishing.

Examples

Ecological Role of Mosses

Funaria and other mosses play a vital role in soil formation, nutrient cycling, and water retention in various ecosystems, particularly in boreal forests and peatlands.

Frequently Asked Questions

▶What is the ploidy level of the spores produced in the Funaria capsule?

The spores produced in the Funaria capsule are haploid (n). They are formed through meiosis within the archesporium and develop into the gametophyte generation.

Topics Covered

BotanyPlant KingdomBryophytesPlant AnatomyMorphology
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