Pteridophytes: Characteristics, Classification and Life Cycle

Gymnosperms, Pteridophytes and Angiosperms all belong to the Tracheophytes family of green plants. It has a vascular network made up of xylem, phloem, and xylem with a well-developed branching, autonomous, and dominating sporophyte. This monophyletic group was established around 420 million years ago.

Pteridophytes are seedless vascular plants with spores that develop freely into gametophytes, unlike higher Tracheophytes. However, only a few members have heterospory or a single megaspore count.

Pteridophytes are a complex, varied category that represents both different evolutionary clades and antiquity. They have been categorized in a number of ways. For ages, plants that looked like ferns ruled the landscape for hundreds of millions of years. Pteridophytes inherit several features from their forefathers. Unlike other members of the Plant Kingdom, Pteridophytes reproduce via spores.

Characteristics of the Pteridophyta

1. According to one idea, life began in the oceans and gradually evolved on dry land over millions of years. Pteridophytes were among the first plants to appear on the surface of the earth.
2. Pteridophytes reproduce by spores rather than seeds. They lack xylem vessels and phloem partner cells, despite having vascular tissues.
3. Roots, stems, and leaves are well-differentiated in the plant body.
4. The sporangium is the structure in which spores form. They are frequently homosporous, which means they produce only one type of spore. The whisk ferns and Tmesipteris are homosporous pteridophytes examples. They can, however, be heterosporous, meaning that two types of spores can be formed. Thus, the heterosporous pteridophytes are those which produce two types of spores.
5. Sporophylls are sporangia-bearing leaves. The tip of the leaves folds inwards to protect the most susceptible areas of the plant as it grows.
6. Antheridia refers to male sexual organs, while archegonia refer to female sexual organs, are found in them.
7. Both the sporophyte and gametophyte generations exist in pteridophytes. The primary plant body is the diploid sporophyte. Therefore, they exhibit actual generational transition, also called alternation of generation.

Pteridophyta Life Cycle

Pteridophytes have generations that alternate. Their life cycle is similar to that of seed-bearing plants; however, unlike mosses and seed plants, pteridophytes have separate and free-living generations of haploid gametophyte and diploid sporophyte. The sexuality of pteridophytic gametophytes is divided into three categories:

1. Individual gametophytes are dioecious, meaning they produce either antheridia and sperm or archegonia and egg cells.
2. Monoecious means that each gametophyte can produce both antheridia and archegonia and function as both males and females.
3. The antheridia mature before the archegonia in a protandrous situation.
4. The archegonia matures before the antheridia, making it protogynous.

Classification of Pteridophyta

Pteridophyta is divided into four categories:

Psilopsida

• They are the most rudimentary of the bunch

• The photosynthetic, dichotomously branching stem

• Rhizoids can be found

• In most of the plants, the leaves are missing

• A homosporous synangium is a sporophyte

• Psilotum and Tmesipteris are two examples

Lycopsida

• Club moss is the popular name for them

• Plant body having adventitious root, stem, rhinophores, and leaves that are well-differentiated

• It depends on whether the sporophyte is heterosporous or homosporous

• Selaginella and Lycopodium are two examples

Sphenopsida

• Horsetail is the common name for this plant

• The underground rhizome’s nodes develop root, stem, and scaly leaves

• They have a well-differentiated plant body

• On strobila, homosporous sporangia are carried

• Equisetum is a good example.

Pteropsida

• A fern is a common name for this plant

• Plant body with stem, roots, and leaves that are well-differentiated

• It depends on whether the sporophyte is homosporous or heterosporous

• Multiflagellate antherozoids

• Pteris, Dryopteris and Adiantum are other examples

Examples

Whisk Fern, Dicksonia, Lycopodium, Equisetum, Selaginella, Man fern, Silver fern, Pteris, Adiantum and Dryopteris are some of the most common Pteridophyta species.

The difference between bryophytes and pteridophytes:

1. Bryophytes are plants with a leafy or thalloid body. Pteridophytes, on the other hand, are made up of roots, stems, and leaves.
2. Bryophytes lack vascular tissue, but Pteridophytes have it.
3. Pteridophytes have a good vascular system, but Bryophytes have not.
4. True stems and leaves are absent in Bryophytes, whereas true stems and leaves are present in Pteridophytes.
5. Bryophytes have stalked Antheridium, whereas Pteridophytes have sessile Antheridium.
6. Gametophytes are dominant in bryophytes. The sporophyte, on the other hand, is dominant in pteridophytes.