Phylum: Charophyta Family: Zygnemataceae
Spirogyra C.G. Nees
Very common in relatively clear eutrophic water, developing slimy filamentous green masses. Zygospores are required to identify to species
References:
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition) The Freshwater Algal Flora of the British Isles