Pteridophyta

A fern plant is a pteridophyte.

Ferns are lower vascular plants. They contain vascular tissue which is made up of xylem and phloem and helps in conduction of water and nutrients to all parts of the plant body. Pteridophytes are usually found in damp, shady places or in the gardens, and on the hills where temperature is low.

The main plant body represents a sporophytic (diploid) generation and has roots which penetrate the soil to absorb water, and minerals.

The leaves (fronds) of sporophyte grow on thick, horizontal underground stem or rhizome which bears adventitious roots. The young leaves and the base of frondsare covered by dry brown scales (ramenta).

The young leaves and leaflets are characteristically circinately coiled structures. The axis of the leaves is called rachis and leaflets on both sides of rachis are called pinnae. The divisions of pinnae are known as pinnules.

On the under surface of the leaves, develop spore-producing bodies called Sporangia in groups, called sori (sorus) which may or may not be covered by multicellular structure called indusium. The sporogenous tissue in the sporangia undergoes meiosis to produce haploid spores.

The spores on dispersal germinate into an independent, small thallus-like body, the gametophyte, called prothallus. The prothallus bears antheridia and archegonia which produce male and female gametes respectively. The gametes fuse and the zygote develops into a diploid sporophyte.

The young embryo absorbs nutrients and water from the gametophyte until its roots and leaves are formed. The gametophyte then dies.

Gametophyte grows independent of sporophyte, and it lives for a short period of time but a new sporophyte is temporarily dependent upon a tiny gametophyte. The gametophytic and sporophytic phases alternate as in bryophytes.