Classification of Plant Kingdom

Classification of Plant Kingdom

In the year 1883, Eichler has classified the Botanical world as under:

1. Cryptogamous plants

There are no flower and seed in these types of plants. These are classified into the following groups:

Thalophyta

1. This is the largest group of the plant kingdom.
2. The body of the plants in this group is thalus like i.e., plant are not differentiated into root, stem and leaves.
3. There is no conducting tissue. It is divided into two groups :
      (a) Algae
      (b) Fungi
(a) Algae
1. The study of algae is called Phycology.
2. The algae normally have chlorophyll and autotrophic mode of nutrition.
3. Its body is thalus like. It may be unicellular, colonial or filamentous.
Useful Algae:
1. As a food : Porphyra, Ulva, Surgassum, Laeminaria, Nostoc etc.
2. In making Iodine : Laeminaria, Fucus, Echlonia etc.
3. As a manure : Nostoc, Anabana, kelp etc.
4. In making medicines : Chloreloline from Chlorella and Tmcher iodine is made from Laminaria.
5. In research works: Chlorelh Acetabularia, Belonia etc.

(b) Fungi
1. Study of fungi is called Mycology.
2. Fungi is chlorophyll less, central carrier tissue less, Thalophyta.
3. Accumulated food in fungi remains as Glycogen.
4. Its cell wall is made up of chitin. Ex. Albugo, Phytophthora Mucor etc.
Fungi may creates serious diseases in plants. Most damage is caused by rust and smut. Main Fungal diseases in plants are as :
White rust of crucifer, Loose smut of wheat, Rust of wheat, early Blight of potato, Red rot of sugarcane, Tikka diseases of groundnut, Wart disease of potato, Brown leaf spot of rice, Late blight of potato, Damping off of seedlings etc.
» Rhizopus is a fungi commonly known as 'bread mould'.

Bryophyta

This is the first group of land plants. In this division approximately 25000 species are included.
1. In bryophyta there is lack of Xylem and phloem tissue.
2. Plant body may be of thallus like and leafy erect structure as in moss.
3. They lack true roots, Stem and leaves.
4. This community is also called Amphibian category of the plant kingdom.
» Water conduction takes place in mosses through parenchyma.
» The moss namely Sphagnum is capable of soaking water 18 times of its own weight. Therefore, gardeners use it to protect from drying while taking the plants from one place to another.
» The Sphagnum moss is used as fuel.
» The Sphagnum moss is also used as antiseptic.

Pteridophyta

The plants of this group is mostly found in wet shady places, forests and mountains.
1. The body of plants is differentiated into root, stem, and leaves. Stem remains as normal rhizome.
2. Reproduction occurs by spores produced inside the sporangia. Sporangia bearing leaf of a fern is called Sorus .
3. Gametophytic phase is short lived. The diploid zygote develops into an embryo.
» Gametophyte is called prothallus in pteridophytes.
4. Plants of this community have conducting tissues. But Xylem does not contain Vessels and Phloem does not contain companion cells.
Examples : Ferns, Azolla, Pteridium, Lycopodium etc. In the neack cell of archegonium of fern one binucleated cell is present.