Chlamydomonas lies under the division algae, due to its defining characteristics. It contains chlorophyll a and b, which give it a green color and enable it to perform photosynthesis, a key feature of this division. Chlamydomonas is also unicellular, allowing it to efficiently absorb nutrients and carry out photosynthesis in aquatic environments. They lack vascular tissues.

Furthermore, the cell wall of Chlamydomonas is made of cellulose, a common component found in the cell walls of many plants and algae. It has two anterior flagella that facilitate movement in water, another characteristic typical of green algae. These traits clearly place Chlamydomonas within the Algae division.