Anoxygenic photosynthesis is characteristic of:

Anoxygenic photosynthesis occurs in certain bacteria (like the purple non-sulfur bacterium Rhodospirillum) where oxygen is not evolved because they use ${\text{H}}_2\text{S}$ or organic compounds as electron donors instead of water. Algae like Spirogyra and Chlamydomonas perform oxygenic photosynthesis.