Cryptogams (Cryptogamae)
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- Опубликовано: 26 авг 2024
- Let’s learn about cryptogams (Cryptogamae) today.
Cryptogams refer to the flowerless and seedless plants.
What are cryptogams?
Cryptogams are flowerless and seedless plants that is these plants bear no flowers and fruits.
The word cryptogams (cryptogamae) means hidden reproduction. It is made up of two Greek words “kryptos” which means concealed and “gamos” which means marriage. Cryptogams include all non-seed bearing plants.
A.W. Eichler in 1883, classified the whole plant kingdom into two sub-kingdoms such as cryptogams and phanerogams. This is the traditional of classification of plants.
Characteristic Features of Cryptogamae:
1. These are lower plants and bear no flowers, seeds and fruits.
2. These reproduce vegetatively, asexually and sexually.
3. Vegetative reproduction takes place cell division or fragmentation while Asexual reproduction takes place by the means of spores.
4. Sexual reproduction takes place by fusion of male and female gametes. Sexual preproduction can be of isogamous, anisogamous and oogamous type. Isogamy is seen in primitive cryptogams while oogamy takes place in advanced cryptogams.
5. Advanced cryptogams such as liverworts, mosses, pteridophytes and algae undergo alternation of generation i.e. these go through two phases to complete their life cycle. The two phases are sporophytic phase and gametophytic phase.
6. Sporophytic phase is characterized by asexual reproduction while in gametophytic phase sexual reproduction takes place.
7. The sporophytic phase is the diploid stage while the gametophytic phase is the haploid stage.
8. The two phases occur in alternation i.e. one after the other.
Classification of Cryptogamae: Cryptogams are further divided into 3 groups:
1. Thallophyta
2. Bryophyta
3. Pteridophytes
What are Thyllophyta?
These include lower cryptogams such as algae, fungi, bacteria, slime molds and lichens. These are the simplest plants where the body is not differentiated into roots, leaves and stems. The simplest thallophyte are bacteria. These are aquatic plants that can grow in fresh as well as marine water. These lack vascular system. Reproduction can be vegetative by fragmentation, asexual by forming asexual spores and sexually by forming unicellular sex organs.
What are Bryophyta?
Bryophyta are photosynthetic thallus-like plant body with no vascular system. These are terrestrial plants with some plants being aquatic. These are generally found in damp and moist places. These include liverworts, horned liverworts and mosses. These have rhizoids (root like structure) for anchorage.
What are Pteridophytes?
These are photosynthetic vascular plants that have well differentiated plant body. These are also known as vascular cryptogams. These are most advanced of all cryptogams. Pteridophytes include Ferns, Horsetails and Clubmosses.
Let’s see what we learned.
1. Cryptogams are seedless and flowerless plants.
2. Cryptogams are divided into 3 subdivisions: Thallophyta, Bryophyta and Pteridophyta.
3. Thallophyta are the primitive cryptogams that have thallus-like plant body and are aquatic.
4. Bryophyta are also thallus-like structure that can grow on both land and water.
5. Pteridophyta are advanced form of cryptogams that have well-differentiated plant body with vascular system.
In the most accepted five kingdom classifications by Whittaker, bacteria are placed as a separate kingdom known as Kingdom Monera and not included under the plantae kingdom. In the same way, fungi are also excluded from plant kingdom and placed separately as Kingdom Fungi as these lack chlorophylls which is the characteristic feature of Plantae Kingdom.
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