A fern is a sort of plant with about 12,000 species known. They also bear roots, leaves and stalks like other vascular plants but they lack seeds and blossoms.
The expression pteridophyte also refers to ferns. A pteridologist research about ferns and lycophytes. Fossil record indicates that they evolved 360 million years back in the Carboniferous period but vast majority of those living ferns are approximately 145 million years old that evolved in the Cretaceous. They’re not so significant from the commercial point of view but are developed for ornamentation, food or remediating soils. Some are weeds and a few hold special place in mythology, art and culture.
Ferns are vascular plants differing from lycophytes by having leaves that are true. They differ from gymnosperms and angiosperms in lacking seeds and blossoms but bear spores. Their life cycle reveals alternation of production which means it is composed of diploid sporophytic and a haploid gametophytic stage. A spore grows by mitosis and creates gametophyte which develops photosynthetic prothallus. A mobile, flagellated sperm fertilizes the egg that’s connected to the prothallus. A zygote that’s currently diploid produces sporophyte by mitosis.
They prefer to stay in a huge array of habitats ranging from distant mountain elevations, to arid desert stone faces, to bodies of water or in open areas. Generally they prefer four kinds of habitats namely moist, shady forests; crevices in rock faces, particularly when sheltered from the complete sun; acidity wetlands such as bogs and swamps; and tropical trees, where many species are epiphytes.
Many are known to produce relationships with mycorrhizal fungi. The spores are rich supply of lipids, protein and carbs are consumed by a few animals. The stem is generally a underground rhizome but sometimes it’s a ground creeping stolon or semi-woody tree trunk. The leaves are green and photosynthetic and are called fronds due to their horizontal arrangement. Tropophylls participate only in photosynthesis such as the leaves of other vascular plants. Sporophylls produce spores and in comparison with the scales of pines. In addition they photosynthesize like tropophylls. Brophophylls produce abnormally high number of spores. They are fibrous like other vascular plants.
Prothallus is green, photosynthetic structure generally 1 cell thick. It’s heart of bladder shaped measuring 3-10 mm long and 2-8 mm wide. It produces gametes in the kind of antheridia and archegonia. Anteridia are small spherical structures which produce flagellated sperms. Archegonia are flask-shaped structures which produce single egg. Rhizoids are root like construction that absorbs water and minerals. They anchor prothallus to dirt.