1.

Which group of plant is known as first vascular and true land plants? Write their characteristics in detail.

Answer»

1. Pteridophytes are known as first vascular and true land plants. 

2. Habitat: Pteridophytes grow in moist and shady places, e.g. Ferns, Horsetail. Some are aquatic (Azolla, Marsilea), xerophytic (Equisetum) and epiphytic (Lycopodium). 

3. Plant body: It is differentiated into root, stem and leaves. 

4. Primary root: The primary root is short lived and is soon replaced by adventitious roots. 

5. Stem: The stem may be aerial or underground. 

6. Leaves: This group contains plants with pinnate (feather – like) leaves. Leaves may be scaly (e.g. Equisetum), simple and sessile (e.g. Lycopodium), small (microphylls e.g. Selaginella) or large (macrophylls) and pinnately compound (e.g. Nephrolepis l Ferns). 

7. Vascular tissues: In these members xylem consists of only tracheids and phloem consists of only sieve cells. 

8. Secondary growth: Secondary growth is not seen in pteridophytes due to absence of cambium. 

9. Alternation of generations: Pteriodphytes show heteromorphic alternation of generations in which the sporophyte is diploid, dominant, autotrophic and independent. Gametophyte is haploid multicellular, generally autotrophic and short lived.



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