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Fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known by some as Filicophyta. A fern is defined as a vascular plant that lacks seeds, and that reproduces by shedding spores to initiate an alternation of generations. New fronds arise by circinate vernation (leaf formation by unrolling).
1 Fern life cycle
The life cycle of a typical fern consists of two distinct stages or generation phases (see alternation of generations), proceeding as follows:
- A sporophyte phase that produces spores by meiosis
- A spore grows by cell division into a haploid prothallus (a gametophyte phase)
- Prothallus produces gametes
- Male gamete fertilizes a female gamete
- The fertilized gamete ( zygoteIn biology, a zygote is the result of fertilization. That is, two haploid cells—usually (but not always) a sperm cell from a male individual and an ovum or ovule from a female—merge into a single diploid cell called the zygote''. The zygote then undergoes) grows by cell division into a diploidDiploid cells have two copies of each somatic chromosome (non-sex chromosomes), usually one from the mother and one from the father. Most somatic cells (body cells) of higher organisms are diploid or polyploid (three or more copies of each chromosome, oft sporophyte (the "fern")
2 Fern structure
A sporophytic fern consists of:
- RhizomeIn botany, a rhizome is a horizontal, usually underground stem of a plant that often sends out roots and shoots from its nodes. Also called a creeping rootstalk or rootstock. Many plants have rhizomes that serve to spread the plant by vegetative reproduct: Creeping stemA stem is the above ground axis of a vascular plant. The young stem develops in the germinating seedling from embryonic tissue known as the hypocotyl . Lengthening of the hypocotyl lifts the cotyledon(s plumule (leaf precursor tissues), and terminal or ap, sometimes underground, absorbs nutrientNutrients and the body A nutrient is any element or compound that is necessary for or contributes to an organism's metabolism, growth, or other functioning. There are six nutrient groups and these can be divided into those that provide energy and those ths, anchors plant
- FrondFrond refers to the leaf structure of ferns. The term is colloquially applied to the leaves of palms, cycads, and other plants with pinnately compound leaves. A significant difference is that, unlike the leaves of the latter, fern fronds bear the reproduc ("fern leafThis article is about the leaf a plant organ. See Leaf (disambiguation) for other meanings. In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin, to expose the chloroplast con"): green, photosynthesizes
- Spores develop on surface (usually underside)
- Petiole: stem-like part of leaf
A gametophytic fern contains:
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