Over 400; see text Spirogyra (common names include water silk, mermaid's tresses, and blanket weed) is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is characteristic of the genus.

[9] In vegetative reproduction, fragmentation takes place, and Spirogyra simply undergoes intercalary cell division to extend the length of the new filaments.

Specifically, in stemming toxic runoff from mines (where they are often found occurring naturally)[11] and from municipal wastewater.

[12] Spirogyra species, such as S. varians, are also being researched for potential pharmaceutical usage due to their high nutrient densities.

American jazz fusion band Spyro Gyra was named after this genus of algae.