Blue-green algae (cyanobacteria) have been known for centuries. They were likely observed even in ancient times due to their prevalence in various environments.

The scientific understanding of blue-green algae has evolved over time, with significant contributions from many researchers. While Gregorio Velasquez was a prominent Filipino botanist and phycologist, he is known for his contributions to the study of algae in the Philippines, particularly diatoms and other microalgae, not blue-green algae specifically.