Ferns are large and important group of plants and are represented by about by 10,000 species. Their ability to adapt to diverse habitat and capacity of vegetative multiplication enable them to be highly successful in the modern era. Ferns are distributed right from the equator to the polar regions. They grow in damp and shady places under xeric conditions. Some are epiphytic and can grow on tree trunks in moist forests and some are free floating forms. Sizes vary from a few milimetres (Azolla) to several metres in tree ferns (Cyathea).
The plant body is perennial and represented by rhizomes, roots and leaves. The characteristic feature of ferns is the dual functions of its leaves. They produce spores along the margin or on the lower surface of the leaf and also manufacture food by photosynthesis. Some important India ferns are: Ophioglossum, Osmunda species (royal ferns; interrupted fern, cinnanhn fern) which are found in South India and the Himalayas. Ferns are ornamental and also produce fibers which are used for the germination of epiphytic orchids in a nursery.