Basics:Ferns are non flowering plants that grow everywhere except really hot deserts or really cold regions. There are approximately 10,000 species worldwide. Most ferns grow in damp, shady areas so the best place to find them are along streams or in cracks of rocks and cliffs. Ferns are among the oldest plants on earth and go way back to about 350,million years.
Structure of a fern:The leaves of ferns are fairly large and have pointy tips. Each leaf of a fern is termed a megaphyll and has a branched system of veins. Some say that megaphylls evolved by the formation of webbing between many separate branches growing close together, Most ferns have leaves commonly called fronds. These fronds are compound, meaning each leaf is divided into several leaflets. The frond grows as its coiled tip (fiddlehead) unfurls. The leaves may grow directly from a prostrate stem or can have upright stems many meters tall. The leaf can only live about one or two years. Ferns have well developed stems and roots as well. The stem stores food that the plant needs to grow. A fern will continue growing as long as the stem stays alive. The stem can grow upright above the ground, horizontally along the ground, or even underground. The stem can live for 100 years or more. The roots anchor the stem to the ground and absorb water and nutrients. The root can live about the same as the stem.
Life cycle of a fern: After a fern spore settles in a favorable place, it develops into a small, heart shaped gametophyte that sustains itself by photosynthesis. Most ferns are homosporous; each gametophyte has both male and female sex organs, but the archegonia and antheridia usually mature at different times, assuring cross-fertilization between gametophytes. Fern sperm, like this of club mosses and horsetails, use a flagellum swim through moisture from antheridia to eggs in the archegonia and then fertilize the egg. A sex attractant secreted by archegonia helps direct the sperm. A fertilized egg develops into a new sporophyte, and the young plant grows out from an archegonium of its parent, the gametophyte. The spots on the underside of reproductive leaves (sporophylls) are called sori. Each is a is a cluster of sporangia, which release the spores that give rise to gametophyes. *The Life cycle of a fern was taken from : Biology, Adisson Wesley, Third Edition.Copyright 1987, 1990, 1993 by The Benjamin/Cummings Publishing Company, Inc.