Difference Between Homosporous and Heterosporous Pteridophytes

Key Difference – Homosporous vs Heterosporous Pteridophytes

Pteridophytais the largestphylumof thekingdomPlantae. They are the second most diverse land plants afterangiosperms. They are a type ofvascular plantswhich possessesxylem and phloemtissues. Pteridophytes reproduction mainly occurs via thespores. They do not produce seeds. Depending on the type and the size of the spores, Pteridophytes can be of two types; Homosporous or Heterosporous. Homosporous pteridophytes produce only one type of spores that are same in size and cannot be distinguished as male or female spores. This spore contains both male and female parts. Most of the pteridophytes are homosporous. Heterosporous pteridophytes produce two types of spores that are in different sizes, and their male and female spores can be distinguished. Therefore, thekey differencebetween homosporous and heterosporous pteridophytes is that thehomosporous pteridophytes produce one type of spores that are same in size whereas heterosporous pteridophytes produce two types of spores that are different in sizes.

CONTENTS

1.Overview and Key Difference
2.What is Homosporous Pteridophytes
3.What is Heterosporous Pteridophytes
4.Similarities Between Homosporous and Heterosporous Pteridophytes
5.Side by Side Comparison – Homosporous vs Heterosporous Pteridophytes in Tabular Form
6.Summary

What are Homosporous Pteridophytes?

Homosporous pteridophytes are vascular plants which produce only one type of spores that are same in size. Most of the pteridophytes are homosporous. The spore cannot be differentiated as male or female in homosporous pteridophytes. These plants produce one type of sporangium bearing the spores. The spore contains both the male and female.

Hence, the spore results in雌雄同株的gametophytewhich bears both male and female parts (antheridia and archegonia respectively) in the same plant. Some examples for homosporous pteridophytes areLycopodium,Equisetum, etc.

What are Heterosporous Pteridophytes?

Heterosporous pteridophytes arefernswhich produce two types of spores that differ in size or morphology. These two types of spores are known asmicrospores and megaspores(male and female spores respectively). Microspores are small in size while megaspores are larger. Microspores are embedded in microsporangia, and they develop into male gametes. Megaspores are embedded in megasporangia and develop into female gametes. Microspores are high in number whereas megaspores are less in number.

从megaspo雌配子体的发展res begins when the megaspores are residing inside the megasporangium. Megaspore produces the female gametophyte that bears archegonia. The development of the male gametophyte is similar to the female gametophyte. Microspore produces male gametophyte that bears antheridia. The resulting plants aredioeciousdue to the heterosporous nature of these plants. The gametophytes are depending on the sporophytes for nutrition. Therefore, the sporophytic generation is the dominant generation in heterosporous pteridophytes. Examples of heterosporous pteridophytes areSelaginella, Marseliaetc.

What are the Similarities Between Homosporous and Heterosporous Pteridophytes?

• Both have a dominant sporophytic generation.
• Both types develop into gametophytes.
• In both types, the gametophyte obtains the nutrition from the sporophyte.

What is the Difference Between Homosporous and Heterosporous Pteridophytes?

Homosporous Pteridophytes vs Heterosporous Pteridophytes
Homosporous pteridophytes are the vascular plants that produce only one type of spore. This spore contains both male and female parts.	Heterosporous pteridophytes are the vascular plants that produce two types of spores, and thus the male and female parts can be distinguished.
Size
All spores are the same size in homosporous pteridophytes.	The spores are of different sizes – Microspores are smaller in size whereas megaspores are larger in size.
Gametophyte
Homosporous pteridophytes produce only one type of gametophyte containing both male and female parts. Hence gametophyte is monoecious.	Produce two types of gametophytes: male gametophytes (microspores) and female gametophyte (megaspores). Hence gametophyte is dioecious.
Examples
Lycopodium, Equisetum.	Selaginella, Marselia.

Summary –Homosporous vs Heterosporous Pteridophytes

Pteridophytes or ferns belong to the class of vascular plants. Depending on the life cycle of the pteridophytes, it can undergo alternation of generation based on homospory or heterospory. Homospory is a phenomenon in which only one type of spore can be seen. Such ferns are referred to as Homosporous Pteridophytes. Heterospory is the condition in which the plant is capable of producing two types of spores. Such pteridophytes are referred to as Heterosporous Pteridophytes. Spores are found inside sporangia. Then they are developed into gametophytes. Homosporous pteridophytes produce one type of gametophyte bearing both male and female gametes. Heterosporous pteridophytes produce two types of gametophytes; male and female gametophytes bearing male and female gametes separately. This is the difference between homosporous and heterosporous pteridophytes.

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Reference:

1.Haufler, Christopher H. “Homospory 2002: An Odyssey of Progress in Pteridophyte Genetics and Evolutionary Biology: Ferns and other homosporous vascular plants have highly polyploid chromosome numbers, but they express traits following diploid models and, although capable of extreme inbreeding, are predominantly outcrossing | BioScience | Oxford Academic.” OUP Academic, Oxford University Press, 1 Dec. 2002.Available here
2.“Heterospory and Seed Habit in Pteridophytes | Botany.” Biology Discussion, 16 Sept. 2016.Available here

Image Courtesy:

1.’Equisetopsida’By Rror – Own work,(CC BY-SA 3.0)viaCommons Wikimedia
2.’Selaginella-sp’(CC BY-SA 2.1 es)viaCommons Wikimedia