Question

A pteridophyte which fixes nitrogen is
1. Azolla
2. salvinia
3. Pteris
4. Selaginella

Answer 1

Correct Answer - Option 1 : Azolla

Concept:

• Pteridophyta: Plants from this group have well-developed roots, stem and leaves, and separate tissues for conduction of food and water. But, they do not bear flowers and fruits.

Explanation:

• Azolla is a free-floating aquatic fern (pteridophyte).
• There are six species of Azolla – Azolla Carolina, Azolla nilotica, Azolla filiculoids, Azolla Mexicana, Azolla microphylla and Azolla pinnata.
• They are extremely reduced in form and specialized, looking nothing like the typical fern but more resembling duckweed or some mosses.
• Under optimal conditions, they form a symbiotic relationship between the cyanobacterium Anabaena azollae and fix a substantial amount of nitrogen
• Due to their ability to fix nitrogen, they are widely used as a bio-fertilizer to improve soil fertility and boosting crop yields.
• Azolla pinnata serves as a great biofertilizer for paddy crops (rice). It increases the nutrient uptake and grain yield of rice.

• Pteris belongs to the class pteropsida of the phylum Pteridophyta. It is a homosporous pteridophyte
• Selaginella:  Also called Little club moss or spike moss or Bird’s nest moss.
• Most of the species of selaginella are ‘’Drought Escapers’’, so they are called Resurrection plants.
• Salvinia is a free-floating fern belonging to the family Salviniaceae. It is a heterosporous pteridophyte producing two different types of spores microspores & megaspores