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 are flowerless and seedless plants. These plants bear no flowers and fruits. 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 traditional of classification of plants.
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Characteristic Features of Cryptogamae
Following are the important features of cryptogams:
- These are lower plants.
- These bear no flowers, seeds, and fruits.
- These reproduce vegetatively, asexually and sexually.
- Vegetative reproduction takes place cell division or fragmentation.
- Asexual reproduction takes place by the means of spores.
- Sexual reproduction takes place by fusion of male and female gametes. It can be of an isogamous, anisogamous and oogamous In isogamy, gametes of similar size, shape, and behavior fuse together. It is seen in primitive cryptogams. In anisogamy, the two fusing gametes slightly differ in size and behavior. In oogamous type, the female gamete is large and non-motile while the male gamete is smaller in size and motile. In oogamy, the female gamete is known as megagamete and the male gamete is known as microgamete, antherozoids or spermatozoa. Oogamy takes place in advanced cryptogams.
- 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 a sporophytic phase and gametophytic phase.
- Sporophytic phase is characterized by asexual reproduction while in gametophytic phase sexual reproduction takes place.
- The sporophytic phase is the diploid stage while the gametophytic phase is the haploid stage.
- The two phases occur in alternation i.e. one after the other.
Classification of Cryptogamae
Cryptogams are further divided into 3 groups such as:
These include algae, fungi, bacteria, and lichens. These are the simplest plants where the body is not differentiated into roots, leaves, and stems. The simplest thallophytes are bacteria. These are aquatic plants that can grow in fresh as well as marine water. These lack vascular system.
These include liverworts, horned liverworts, and mosses. These are also an undifferentiated plant with no vascular tissues. These have rhizoids (root like structure) for anchorage. These are generally found in damp and moist places. These can grow both on land and in water. These are simplest of all land plants and also known as amphibians of the plant kingdom.
These include all kinds of ferns. These have well-differentiated plant body and vascular system is also present in them. These are also known as vascular cryptogams. These are most advanced of all cryptogams.
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 the plant kingdom and placed separately as Kingdom Fungi as these lack chlorophylls which are the characteristic feature of Plant Kingdom.