Introduction to Algae

2020-10-31T00:20:00.004-07:00

The branch of Botany which deals with study of ‘algae’ is called Phycology or Algology. Algae are chlorophyllous, non-vascular thallophytes. These are characterized by non-vascular plant body, simple, unicellular, non-jacketed sex organs except the members of Charophyceae in which multicelllular sex organs are present surrounded by sterile cells jacket.

We are familiar with algae in the form of pond scum or algal blooms. These are diverse group of organisms mostly found in aquatic habitats, freshwater or saltwater. The term Algae (singular-Alga) was introduced by Linnaeus in 1753 which is Latin word for seaweeds. Algae are heterogeneous group of organisms with different forms and sizes. They may exist single or live in colonies, they may be unicellular or multicelllular. They are mostly thalloid but sometimes take on a leafy appearance as seen in seaweeds. The size of algae can be as small as 0.3 µm in diameter to about 60 meters as seen in fronds of giant kelp. They are helpful to us because of the ability to conduct photosynthesis.

M.O.P Iyengar is regarded as ‘Father of Modern India Algology’. R.N.Singh has written famous monograph on Algae ‘Role of BGA in Nitrogen Economy of Indian Agriculture’.

F.E. Fritsch (1935, 1945) proposed a most comprehensive system of classification of Algae in his book “The Structure and Reproduction of the Algae”. He has given ‘algae’ the rank of division and divided it into 11 classes. The basis of his classification was pigment composition, flagella and reserve food material.

1. Chlorophyceae

2. Xanthophyceae

3. Chrysophyceae

4. Bacillariophyceae

5. Cryptophyceae

6. Dinophyceae

7. Chloromonadineae

8. Euglenineae

9. Phaeophyceae

10. Rhodophyceae

11. Myxophycea

Classification of Plant Kingdom

2020-07-04T04:41:00.012-07:00

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.

Botany Learners

Introduction to Algae

Classification of Plant Kingdom