Pteridophyta-Reptiles of Plant Kingdom
Pteridophytes plants are the first vascular & terrestrial plants to have fully terrestrial adaptations on Earth.
They are considered to be the first members of the Tracheophyta group.
Pteridophytes are also known by Reptiles of Plant Kingdom.
While after these there is talk of gymnosperm and angiosperm plants.
They are also placed in the Tracheophyta group. Pteridophytes plants are more developed plants than bryophyte plants and algae.
And in these vascular bundles-xylem and phloem (vascular bundles-xylem & phloem) are found.
Note- Vascular bundles are found only in Pteridophytes, gymnosperms and angiosperm trees, so they are kept in a separate category called tracheophyta.
Whereas vascular tissue (xylem and phloem) is not present in algae and bryophyta.
Well developed true leaves, stem & roots are found in Pteridophytes trees.
Characteristics of Pteridophytes
Pteridophytes plants have the following characteristics.
1- Their main plant body is diploid (diploid-2N sets of chromosomes).
2- Throughout their lifetime, the sporophyte stage is diploid and the dominant stage, throughout their lifetime.
Sporophyte is free living, terrestrial and capable of photosynthesis.
4-The sporophyte plant body is multicellular, and produces haploid spores (haploid-1n number of chromosomes) by cell division by meiosis.
5-Most pteridophytes are homosporous, these spores can be of one type, meaning to say that most pteridophytes are homosporous.
6-There are some pteridophytes that are heterosporous, such as, Selaginella, Salvinia etc., they produce two types of spores, the smaller spore is called microspore and the larger spore is called megaspore.
7-Mycospores later develop into male gametophytes, and megaspores later develop into female gametophytes.
Root, stem and leaves are found in pteridophyte plant body. and develops properly.
9-Pteridophytes are the first plants present on earth, in which vascular tissue – xylem and phloem is the most developed.
Their life cycle pattern is haplo-diplontic.
11-Both sexual and asexual reproduction process (asexual & sexual reproduction) is found in them.
11- Fruits, flowers and seeds do not develop in them.
12- In these, a structure similar to leaves is found, which are called sporophylls. Sporangia are present in these sporophylls.
13-Spores are formed in sporangia, which later develop into gametophytes.
14-Pteridophyte is used to make decorative medicine and prevent soil erosion.
15-The sporophyll forms a compact structure called strobili or cone. (In Selaginella, Equisetum)
16-Small leaves are called microphylls (in Selaginella) and large leaves are called macrophylls (in ferns).
Classification Of Pteridophytes
Four main classes of pteridophyte have been divided, whose names are as follows –
(1) Psilopsida – like Psilotum
(2) Lycopsida – example Selaginella, Lycopodium
(3) Sphinopsida – example Equisetum
(4) Pteropsida – like Dryopteris, Adiantum
Reproduction in Pteridophytes
The main plant body is the sporophyte, which produces haploid spores in sporangia by meiosis cell division.
This spore germinates to form a small multicellular free living photosynthetic thalloid gametophyte called prothallus.
But it is important to note here that water is needed for fertilization.
The gametophyte contains male and female reproductive organs. The male reproductive organ is called the antheridium, and the female reproductive organ is called the archegonium.
male gamete called antherozoids is released from the antheridium and reaches the archegonium with the help of water. Where this male gamete fertilizes the egg cell.
As a result of which zygote is formed, this zygote undergoes mitosis cell division to form multi cellular sporophyte.
This female gametophyte plant is attached only to the parent sporophyte.
The development of the zygote into the embryo takes place only in the female gametophyte plant.
Economic importance of Pteridophytes
Pteridophytes are used for
- as ornamental or decoration purpose.
- in making of many important medicines
- due to presence of roots they also used in preventing soil erosion.
Conclusion
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