What is the Difference Between Homosporous and Heterosporous Pteridophytes

The main difference between homosporous and heterosporous pteridophytes is that the homosporous pteridophytes produce only one type of spores whereas the heterosporous pteridophytes produce two types of spores: megaspores and microspores. Furthermore, homosporous pteridophytes produce bisexual gametophytes while heterosporous pteridophytes produce unisexual gametophytes.

Homosporous and heterosporous pteridophytes are two types of pteridophytes classified based on the type of spores produced in the sporophyte. Pteridophytes include ferns, horsetails, and lycophytes.

Key Areas Covered

1. What are Homosporous Pteridophytes
     – Definition, Types of Spores, Lifecycle
2. What are Heterosporous Pteridophytes
     – Definition, Types of Spores, Lifecycle
3. What are the Similarities Between Homosporous and Heterosporous Pteridophytes
     – Outline of Common Features
4. What is the Difference Between Homosporous and Heterosporous Pteridophytes
     – Comparison of Key Differences

Key Terms

Gametophyte, Heterosporous Pteridophytes, Homosporous Pteridophytes, Megaspores, Microspores, Sporangia

What are Homosporous Pteridophytes

Homosporous pteridophytes are the type of pteridophytes that produce only one type of spores in their sporophytes. These spores are equal in their size, shape, and sex. Moreover, these pteridophytes have only one type of sporangia for the production of these spores.

Figure 1: Sporophylls of Clubmoss

The germination of these spores produces a gametophyte, which is bisexual. This means the gametophyte of the homosporous pteridophytes develop both male and female reproductive organs – antheridia and archegonia respectively in the same gametophyte. They produce both male and female gametes in the same gametophyte. The fusion of the gametes forms the embryo, which develops into the sporophyte.

What are Heterosporous Pteridophytes

Heterosporous pteridophytes are a type of pteridophytes that produce two types of spores in the sporophyte. The two types of spores are the microspores and the megaspores. Therefore, the sporophyte bears two types of sporangia known as microsporangia and megasporangia. Microsporangia produce microspores, which are small in size while megasporangia produce megaspores, which are large in size. Generally, microsporangia are considered as male spores while megaspores are considered as female spores. However, it is difficult to assign a sex for the spores since they are a part of the asexual reproduction. These spores are diploid as well.

Figure 2: Salvinia minima

The germination of microspores produces the male gametophyte while the germination of megaspores produces the female gametophyte. Male gametophyte is responsible for the production of male gametes while the female gametophyte is responsible for the production of female gametes. The fusion of male and female gametes produces the sporophyte in the next generation.

Similarities Between Homosporous and Heterosporous Pteridophytes

• Homosporous and heterosporous pteridophytes are two types of pteridophytes which produce different types of spores.
• Both pteridophytes undergo alteration of generations by producing sporophyte and gametophyte in the subsequent generations.

Difference Between Homosporous and Heterosporous Pteridophytes

Definition

Homosporous pteridophytes refer to the pteridophytes that produce only one type of spores that are not separated by sex while heterosporous pteridophytes refer to the pteridophytes which produce two types of spores separated by sex.

Types of Spores

A main difference between homosporous and heterosporous pteridophytes is that homosporous pteridophytes produce only one type of spores, which are small in size while heterosporous pteridophytes produce two types of spores; the small microspores and the large megaspores.

Size of Spores

The spores of homosporous pteridophytes are equal in size while the spores of heterosporous pteridophytes come in two different sizes. Therefore, this is another difference between homosporous and heterosporous pteridophytes.

Sporangia

Also, only one type of sporangia occurs in homosporous pteridophytes while microsporangia and megasporangia are the two types of sporangia produced by heterosporous pteridophytes.

Gametophyte

Furthermore, the homosporous pteridophytes produce only one type of gametophyte while the heterosporous pteridophytes produce two types of gametophytes: male and female gametophyte.

Gametophyte Sex

One other difference between homosporous and heterosporous pteridophytes is that the gametophyte of homosporous pteridophytes is bisexual while the gametophyte produced by the heterosporous pteridophyte is unisexual.

Examples

Some examples of homosporous pteridophytes are clubmoss and puzzlegrass while some examples of heterosporous pteridophytes are Selaginella and Salvinia.

Conclusion

Homosporous pteridophytes are the pteridophytes which produce only one type of spores. The germination of these spores produces a bisexual gametophyte. On the other hand, heterosporous pteridophytes are the pteridophytes which produce two types of spores: microspores and megaspores. The germination of microspores produces the male gametophytes while the germination of megaspores produces the female gametophyte. The main difference between homosporous and heterosporous pteridophytes is the type of spores produced by them.

Reference:

1. “Homosporous and Heterosporous Ferns.” Plant Science 4 U, Available Here

Image Courtesy:

1. “LycopodiumClavatum” By Christian Fischer (CC BY-SA 3.0) via Commons Wikimedia 
2. “Salvinia minima 1” By Kurt Stüber [1] – caliban.mpiz-koeln.mpg.de/mavica/index.html part of www.biolib.de (CC BY-SA 3.0) via Commons Wikimedia