Classification of Algae by Smith

Table of Contents

• Division 1: Chlorophyta
• Division 2: Euglenophyta
• Division 3: Pyrrophyta
• Division 4: Chrysophyta
• Division 5: Phaeophyta
• Division 6: Cyanophyta
• Division 7: Rhodophyta
• Frequently Asked Questions

Gilbert Morgan Smith was an American botanist who gave a system of taxonomy for cryptogams in his two books Cryptogamic Botany, Vol. 1 (1938) and Cryptogamic Botany, Vol. 2 (1950).

He divided algae into seven divisions based on their physiological characteristics such as vegetative cells and motility of reproductive cells. Related classes were included in the division and all the uncertain algae were placed separately in Chloromonadales & Cryptophyceae. Let us look at the seven divisions in brief.

Division 1: Chlorophyta

They are freshwater algae that have chlorophyll, carotenoid and xanthophyll pigments, and their reserve food is starch. They have two classes in this division, chlorophyceae and charophyceae.

Following orders are included in the division: Volvocales, Tetrasporales, Ulotrichales, Ulvales, Schizogoniales, Cladophorales, Oedogoniales, Zygnematales, Chlorococcales, Siphonales, Siphonocladiales and Charales.

Division 2: Euglenophyta

The algae in this division are found in freshwater and stagnant water; their reserve food is paramylon. This division has two orders: Euglenales and Colaciales.

Division 3: Pyrrophyta

They are marine algae that have yellowish-green and brown pigments, their reserve food is starch or oil. This division has three classes: Cryptophyceae, Desmokontae and Dinophyceae.

Division 4: Chrysophyta

This division mainly contains diatoms that are found in saline or fresh water. Their reserve food material is oil or leucosin. They have three classes: Xanthophyceae, Chrysophyceae and Bacillariophyceae.

Division 5: Phaeophyta

Also known as brown algae, they are marine organisms that have fucoxanthin pigment that gives them the characteristic brown colour. Their reserve food material is oil or carbohydrates. They have three classes: Isogeneratae, Heterogeneratae and Cyclosporeae.

Division 6: Cyanophyta

Also known as blue-green algae, they are mostly found on rocks and moist soils in fresh and marine water. Their chief pigment is phycobilin. Their reserve food material is stored as glycogen. This division has one class: Cyanophyceae.

Division 7: Rhodophyta

Also known as red algae, they are found in marine environments. Their chief pigment is phycoerythrin that gives them the characteristic red colour. Their reserve food is floridean starch. This division has one class: Rhodophyceae.

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