Pteridophytes: General Characteristics, Habitat, Size and Plant Body

Have you ever wondered about the first land plants which had true roots, stems and leaves? Neither algae, nor bryophytes! The name carries ‘phyta’. Can you guess now? 
Yes! That’s pteridophytes. 
Pteridophyta is the third division of Plant Kingdom that includes the ferns (‘pteris’ means ferns and ‘phyton’ represents plant) and horsetails. Pteridophytes were the first terrestrial plants with vascular tissues - xylem and phloem. These non-seed bearing plants are considered to be one of the most diverse groups of land plants.

Based on fossil records, pteridophytes are believed to have originated around 350 billion years ago. Wow!! That is even before the dinosaurs ruled the Earth!!

Let us look into some of the general characteristics that all pteridophytes share.

Table of Contents

• Habitat of pteridophytes
• Size of pteridophytes
• Plant body
• Practice Problems
• FAQs

Habitat of Pteridophytes

Cool, shady and moist places are ideal for the growth of pteridophytes. However, some pteridophytes can grow in sandy soil too. Some common habitats of pteridophytes include moist shady forests, crevices of rocks, bogs and marshes, trunks of trees etc.

Interesting fact

Did you know that Selaginella is also known as the resurrection fern as it can come back to life even after staying in a dry state, without water, for 100 years. It can stay alive even after losing up to 75% of body water in a normal dry period and up to 97% of water content under drought conditions. Putting it in water brings it back to life again!

Size of Pteridophytes

Some ferns can be as small as 1 cm tall while some can be as tall as 20 metres in height. Malvi's adder's-tongue fern is the smallest fern which is around 1 cm tall. Azolla is a small fern that is around ⅜ inches to 1 inch in height. The tallest fern is Cyathea australis which is around 20 metres tall!!

Plant body

The main plant body of pteridophytes is a diploid (2n) sporophyte which is well-differentiated into roots, stems and leaves. 

Pteridophytes also exist as an independent thalloid (undifferentiated plant body) known as prothallus that bears the sex organs. This plant body represents the gametophyte generation of their life cycle. 

Stem

The stem is a rhizome and can be of three types -

• Long and creeping
• Short and creeping
• Ascending

Stem bears the leaves and can also photosynthesise in some species of pteridophytes.

Root

Adventitious roots arise from the rhizome stem and help in absorption of water and minerals.

Leaves

Leaves are pinnately compound and are known as fronds. In each frond the leaf lamina is broken into leaflets/pinna that grow along a stalk called rachis. The midrib of each leaflet is called a costa. Sub-leaflets called pinnules are borne on the costa. The stalk below the leaf blade is known as the stipe.

Leaves are green and feathery in appearance and can photosynthesise. Young leaves exhibit circinate ptyxis, i.e., they are tightly coiled like a spring. These resemble the handle of a violin or fiddle and are hence known as fiddleheads. As the young leaves grow, the spirals unwind and the mature leaves are formed.

Types of leaves

Leaves may be small as seen in Selaginella. These are known microphylls. Larger leaves are known as macrophylls and are seen in ferns.

Sporophylls

Sporophylls are the leaves which have spore bearing chambers called sporangia on their undersurface.

In some pteridophytes such as Equisetum and Selaginella, the sporophylls form prominent compact structures known as strobili or cones.
Spore mother cells within the sporangia undergo meiosis to give rise to haploid spores which germinate into haploid gametophytes.

Practice Problems of Pteridophytes

1. If the number of chromosomes in the spore mother cell of a pteridophyte is 28. Then the chromosome number of the spore and the gametophyte will be

a. 28, 14
b. 14, 28
c. 14, 14
d. 28, 28

Solution: The main plant bodies of the pteridophytes is a diploid sporophyte which bears specialised leaves known as sporophylls with sporangia. The sporangia contain diploid spore mother cells which undergo meiosis to produce haploid spores which germinate into haploid gametophytes.
Thus, if chromosome number of diploid spore mother cell = 28
Chromosome number of haploid spore and gametophyte = 28/2 = 14
Hence, the correct answer is option c.

2. Match the following plants to their correct height and choose the correct option below:

a. A - II, B - I, C - III
b. A - I, B - III, C - II
c. A - II, B - III, C - I
d. A - III, B - II, C - I

Solution:

Thus, the correct option is b.

3. Which of the following statements about Selaginella is incorrect?

a. It is a non-seed bearing plant.
b. It can live even after losing 75% of body water during a normal dry period.
c. It can live without water for a few days to a week.
d. It can be brought back to life after putting it in water.

Solution: Being a pteridophyte, Selaginella is a non-seed bearing plant. It can live without water for 100 years and is brought back to life after being put in water. During a normal dry period, it can live even after losing 75% of body water. Thus, the correct option is c.

4. Identify the following images and choose the correct option:

a. A - macrophyll with a single unbranched vein
b. B - microphyll with multiple branched veins
c. A - microphyll with a single unbranched vein
d. B - macrophyll with a single unbranched vein

Solution: Small leaves in pteridophytes are known as microphylls. Larger leaves are known as macrophylls.
A is a microphyll with a single unbranched vein and is connected to the stem without a stalk.
B is a macrophyll with multiple branched veins and is connected to the stem with a stalk.
Thus, the correct option is c.

FAQs of Pteridophytes

Question 1. Why is Selaginella known as the ‘resurrection fern’?

Solution: Selaginella is also known as the resurrection fern because it can survive without water for 100 years and can come back to life once put in water. It can stay alive even after losing up to 75% of body water in a normal dry period and up to 97% of water content under drought conditions. 

Question 2. Why are young leaves of pteridophytes known as fiddleheads?

Solution: Young leaves exhibit circinate ptyxis, i.e., they are tightly coiled like a spring. These resemble the handle of a violin or fiddle and are hence known as fiddleheads.

Question 3. What are pteridophytes? Give examples.

Solution: Pteridophytes are terrestrial plants which do not bear seeds or flowers but have well-developed vascular tissues (xylem and phloem). These plants have a well-differentiated plant body and are considered to be one of the most diverse groups of land plants. Ferns and horsetails are common examples of pteridophytes.

Question 4. Which is the tallest pteridophyte?

Solution: Some ferns can be as small as 1 cm tall while some can be as tall as 20 metres in height. Malvi's adder's-tongue fern is the smallest fern which is around 1 cm tall. The tallest fern is Cyathea australis which is around 20 metres tall.

Other Related Topics

Other Related Topic Of Biology

• Algae characteristics eproduction
• alternation f eneration nd lassification
• Pteridophytes alternation of generations
• Bryophytes