Useful notes on the classification of algae!
For the first time, Aristotle (382-322 B.C.) and his pupil Theophrastus (372-287 B. C.), the father of Botany, classified the plants into three groups, i.e., trees, shrubs, and herbs.
This classification was based on the form and texture of the plants.
Here, they considered the trees to be highest evolved.
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In eighteenth century, Linnaeus (1707-1778) proposed his artificial sexual system of classification. He divided the plant kingdom into twenty five orders or classes. In his last order Cryptogamia, he placed the plants with concealed reproductive organs (flower, etc.). Linnaeus divided his order Cryptogamia into four suborders, i.e., (1) Filices (pteridophytes), (2) Musci (mosses and leafy liverworts), (3) Algae, (algae, lichens and thallose liverworts), (4) Fungi.
The first natural system of classification of the plants was proposed by A. L. de Jussieu (1748-1836) in the end of eighteenth century, who divided the plants into three major groups, i.e., (1) Acotyledones, (2) Monocotyledones and (3) Dicotyledones. His classification was based upon the sexual system of Linnaeus but in improved form. His Acotyledones were like Cryptogamia of Linnaeus.
In 1880, the cryptogamic plants were divided into three major groups, i.e., (1) Thallophyta (algae, fungi and bacteria), (2) Bryophyta, and (3) Pteridophyta.
Before twentieth century only four classes were recognized among algae, i.e., (1) Chlorophyceae (2) Phaeophyceae, (3) Rhodophyceae and (4) Myxophyceae or Cyanophyceae. Diatoms were then included in Phaeophyceae.
Formerly many zoologists placed many motile (flagellate) algae of today in the class Mastigophora of phylum Protozoa.
Rabenhorst in 1863, for the first time placed the Chlamydomonas-Volvox series in the Chlorophyceae of algae.
In the beginning of the twentieth century, the class Xanthophyceae was separated from Chlorophyceae and certain pigmented flagellate types were included in the class. According to Dr. F.E. Fritsch (1935, 1944, and 1945), the algae have been divided into following eleven classes:
- Chlorophyceae
- Xanthophyceae
- Chrysophyceae
- Bacillariophyceae
- Cryptophyceae
- Dinophyceae
- Chloromonadineae
- Euglenophyceae or Euglinieae
- Phaeophyceae
- Rhodophyceae
- Myxophyceae