FERNS Leatherwood Fern
A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. A fern is a vascular plant (plant in which the phloem transports sugar and the xylem transports water and salts.) has true leaves and lacks seeds. Like all vascular plants, it has a life cycle, often referred to as alternation of generations. In ferns the gametophyte is a free-living organism. The life cycle of a typical fern is as follows:
1. A sporophyte (the spore-producing phase in the life cycle of a plant that exhibits alternation of generations) phase produces haploid(meaning simple in Greek, cells bear one copy of each chromosome ) spores by meiosis(cell division that produces reproductive cells in sexually reproducing organisms).
2. A spore grows by cell division into a gametophyte(phase of plant life cycles in which the gametes, i.e., egg and sperm, are produced), which typically consists of a photosynthetic prothallus (the minute primary growth from the spore of ferns, which bears the true sexual organs)
3. The gametophyte produces gametes (often both sperm and eggs on the same prothallus) by mitosis
(division of a single cell into two identical “daughter” cells. )
4. A mobile sperm fertilizes an egg that remains attached to the prothallus. 5. The fertilized egg is now a diploid zygote(the single cell that results from fertilization of an ovum by a sperm) and grows by mitosis into a sporophyte (the typical "fern" plant). Fern structure is made of:
1. Stems: Most often an underground creeping rhizome, but sometimes an above-ground creeping stolon , or an above-ground erect semi-woody trunk
2. Leaf: The green, photosynthetic part of the plant. In ferns, it is often referred to as a frond, but this is because of the historical division between people who study ferns and people who study seed plants, rather than because of differences in structure. 3. Roots: The underground non-photosynthetic structures that take up water and nutrients from soil. They are always fibrous and are structurally very similar to the roots of seed plants. Economic uses Ferns are not of major economic importance, with one possible exception. Ferns of the genus Azolla, which are very small, floating plants that do not look like ferns, called mosquito fern, are used as a biological fertilizer in the rice paddies of southeast Asia, taking advantage of their ability to fix nitrogen from the air into compounds that can then be used by other plants. Other ferns with some economic significance include:
In addition, a great many ferns are grown in horticulture. Misunderstood Names
Several non-fern plants are called "ferns" and are sometimes popularly believed to be ferns in error. These include:
This page is compiled From Wikipedia, the free encyclopedia.
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