Classification of Plant Kingdom

We get refreshed everyday to see the green cover all around. There are big trees, bushes, herbs, climbers, vines, cacti etc. that attract our attention. Approximately 2,60,000 plant species are spread over land and water. Some plants have beautiful flowers with variously coloured petals, some have variously designed leaves fascinating us every time we look at them. The curiosity to know more about these natures’s jewel compel science seekers to do research on these sessile living things. Plants are multicellular eukaryotes with distinct feature of synthesizing their own food with the help of green pigment chlorophyll. All animals including humans depend on plants for their energy requirement. The plants also act as purifier of the atmosphere as they take in carbon dioxide for photosynthesis and release oxygen which animals need to breathe. The Plant Kingdom is divided into four divisions:

1)      Thallophyta

2)      Bryophyta

3)      Pteridophyta

4)      Spermatophyta

The Thallophytes have distinct characters as the plant body is not divided into root, stem and leaves, sex organs are absent or unicellular, non-jacketed and no embryo formation. It is further divided into two sub-divisions:

•        Algae
•        Fungi

The Spermatophyta has two sub-divisions:

• Angiosperms - This group has two classes ; Dicotyledonae and Monocotyledonae
• Gymnosperms –This group also has two classes ; Cycadopsida and Coniferopsida

A. W. Eichler gave the traditional way of classification of in 1883.  He classified Plant Kingdom into two sub-kingdoms –

• Cryptogams – These plants have no flowers, no seeds, reproduction is mainly by spores. Thallophyta, Bryophyta and Pteridophyta are included in this kingdom. The word ‘Cryptogam’ is derived from Greek words ‘Kryptos’ meaning “hidden’” and ‘Gamos’ meaning “marriage”.
• Phanerogams – These are seed bearing plants. This group comprises of Gymnosperms and Angiosperms. Gymnosperms are non-flowering plants with no fruit formation and naked seeds. Angiosperms are flowering plants which produce seed enclosed in fruit.