Pteridophyta is a phylum of plants widely known as ferns. More than 12,000 different species of ferns are distributed worldwide. They are distinguished from flowering plants by not producing seeds. Pteridophyta members reproduce through spores. Ferns were some of Earth's first land plants. They are vascular and have true leaves.
Ferns are strongly distinguished from other plants by their method of reproduction. Instead of producing seeds, they reproduce by making spores--microscopic structures that combine with sperm to produce a new generation. Spores are produced that develop into gametophytes. The gametophyte grows into a tiny heart-shaped structure that develops male antheridia and female archegonia that produce sperm and eggs. Sperm from the antheridia fertilize the egg in the archegonia and the gametophyte will develop into a sporophyte--an adult fern.
Ferns are usually found in border habitats that other plants find hard to survive in. They grow in rock crevices, deserts, on mountains and in moist and shady forests. Some species are epiphytes that grow without soil on the branches of trees.
Ferns have fibrous roots. They are generally considered non-woody plants, but some giant ferns can be considered semi-woody. They have green leaves that provide energy through photosynthesis. New leaves grow out of a tight spiral called a fiddlehead. They also have specialized leaves that produce spores called sporophylls. Ferns grow from a rhizome that sits just on top of the soil.