6. Classification of Plants.
kingdoms Monera, Protista and Fungi of the ‘Five Kingdom’ classification system proposed by Robert Whittaker (1969) for the study of living organisms.
Kingdom plantae :
- Autotrophic living organisms having eukaryotic cells with cell walls .
- Perform photosynthesis with the help of chlorophyll.
- Main source of food for all other living organisms.
- In 1883, Eichler, a botanist, classified the Kingdom Plantae into two sub kingdoms.
- Cryptogams
- Phanerogams
Basis for classification :
- Presence or absence of organs
- The presence or absence of separate conducting tissues for conduction of water and food.
- whether the seeds are enclosed in a fruit or not.
- Finally, plants are grouped depending upon the number of cotyledons in the seeds.
At the higher levels of plant classification :
- Absence or presence of flowers, fruits and seeds, plants are classified as cryptogams or phanerogams.
- Depending upon whether seeds are enclosed within a fruit or not, phanerogams are classified as -
- Gymnosperms
- Angiosperms.
- Angiosperms are further classified as -
- Monocots
- Dicots
Cryptogams :
- It Has Three Divisions
- Division I - Thallophyta
- Division II - Bryophyta
- Division III- Pteridophyta
Division I - Thallophyta:
- Grow mainly in water.
- Do not have specific parts like root-stem-leaves-flowers but are autotrophic due to the presence of chlorophyll, is called algae.
- Algae show great diversity.
- Unicellular or multicellular, and microscopic or large.
- Examples of algae are Spirogyra, Ulothrix, Ulva, Sargassum, etc.
- Some of these are found in fresh water while some are found in saline water.
- Have a soft and fibre-like body.
- Various types of fungi like yeasts and moulds which do not have chlorophyll are also included in this group.