Plant Kingdom

Carolos Linnaeus divided the world of living organisms into two kingdoms: animal kingdom and plant kingdom . There are millions of species of plants. They vary from small size to a large size. On the basis of presence or absence of flowers, all the plants are divided into two major sub-kingdoms: cryptogams and phanerogams.

Sub kingdom: Cryptogams

They are promitive and somplest plants without flowers. They are On the basis of appearance and stage of development, cryptogams are divided into three divisions. They are:

1. Thallophyta,
2. Bryophyta and
3. Pteridophyta.

1. Division: Thallophyta

They are the most primitive and the simplest plants. They may be multicellular or multicellular. They possess following characteristics:

1. Thallophytes may be unicellular or multicellular plants.
2. The plant body is not differentiated into root, stem and leaves.
3. They reproduce both by asexual and sexual method.

Thallophyta is divided into two sub-divisions. They are algae and fungi.

a. Sub-division: Algae

Algae are the green thallophytes which have the following characteristics:

1. Mostly, algae are usually aquatic but few are grown in moist soil.
2. They contain chlorophyll, so they can prepare their food.
3. The cell wall of plants is made up of cellulose.
4. They store food in the form of starch.
5. Reproduction takes place by vegetative, asexual and sexual method.
6. Examples: spirogyra, sea-weeds, volvox, etc.

b. Sub-division: Fungi

Fungi include non-green plants and have following characteristics:

1. They are grown in damp, moist and dark places.
2. They cannot make their own food due to absence of chlorophyll.
3. The fungi consist of network of mycelium which consists of thread like structures called hyphae.
4. They store food in the form of glycogen, and oil globules.
5. They reproduce by vegetative, asexual and sexual method.
6. Examples: mushroom, mucor, yeast, ring worm etc.

2. Division: Bryophyta

Bryophyta have the following characteristics:

1. They are grown in damp, moist and shady places.
2. They contain chlorophyll so they are autotrophic.
3. They need water for fertilization so they are also called amphibian plants.
4. They show distinct alternation of generation in their life cycle.
5. They reproduce by vegetative, asexual and sexual method.
6. Examples: moss, liverworts etc.

 

3. Division: Pteridophyta

Pteridophyta are seedless vascular plants . They are seedless vascular plants and have the following characteristics:

1. They are mostly found in moist, shady and cool places.
2. Plant body is differentiated into roots, stem and leaves.
3. They are vascular plants and bear feather like leaves.
4. They contain chlorophyll so they are autotrophic.
5. They are well developed among all non-flowering plants.
6. Examples: fern, horsetail, paniamala etc.