Pteridophytes are non-flowering, vascular and spore-bearing plants including ferns and fern-allies.
Pteridophytes in India form a conspicuous element of the earth’s vegetation and are important from evolutionary point of view as they show the evolution of vascular system and reflect the emergence of seed habitat in the plants. About 250 million years ago they were the dominant part of earth’s vegetation, but they were largely replaced by the seed bearing plants.
The species of the Pteridophytes grow luxuriantly in moist tropical and temperate forests and their occurrence in different eco-geographically threatened regions from sea level to the highest mountains are of much interest.
This plant group forms a connecting link between non-vascular lower group plants and the higher group seed bearing plants. The Pteridophytes comprises over 300 genera and about 12,000 species and in India by almost 1000 species, of which 47 are endemic to India and some of these species are placed under RET category.
Several species of the Pteridophytes possess medicinal properties and indeed, ferns’ medicinal qualities were recorded as early as 300 B.C. by the Greek philosopher Theophrastus and his Indian contemporaries Sushrut and Charak. The species of the genus Azolla Lam. show symbiotic association with nitrogen-fixing, blue-green algae, Anabaena azollae Strasburger. Due to this property, the Azolla is used as bio-fertilizer by the Agronomist in rice fields in many countries including India.