According to their habitat algae are classified into seven groups.
These are aquatic, free floating or completely submerged algae.
Terestial algae are called Edaphic algae. They live upon or inside the surface of earth. Edaphic algae are classified into two types,
· Saprophytes E.g. Mesotaemium, Botryduium
· Crypyophytes E.g. Nostoc, Anabaena
These are aerial forms of algae. They are found upon trunks of trees, walls, fencing wire, rocks and animals. Aerial algae are classified into four types. They are,
· Epiphyllophytes E.g. Trentepohlia