What is the scietific name for beard algae?

Answer 1

Technically this is a type of red algae, but that classification does not define its appearance. This unwanted algae often shows up on older parts of plants and on slower-growing plants. Black beard algae is a form of "red algae" in the genus Audouinella that commonly attaches to edges of plant leaves or drift wood and is more common in low CO2 water conditions, that are low in most minerals (although often high in iron), carbonates, and pH (although these algae will also grow in alkaline, high pH waters as well).