Family: Filamentous algae without branching; cell body cylindrical; chloroplasts band-, plate- or star-shaped (Illustrations of The Japanese Fresh-water Algae, 1977).
Genus: Filament without branching; cell body cylindrical; one or several chloroplasts band-shaped, spirally arranged within the cell, pyrenoids present; septum with or without folded structure (Guide book to the "Photomicrographs of the Freshwater Algae", 1998). About 300 species (Illustrations of The Japanese Fresh-water Algae, 1977).
Spirogyra sp.
4 chl., 2-3 turns
34 μm diam.
Kiyose
Tokyo, 2001
Movies 
Spirogyra sp.
3 chl. 3 turns
conjugation
35 μm diam.
Japan, 1998
Spirogyra sp.
3 chl.
35 μm diam.
Nishi-Urawa
Saitama, 2001
Spirogyra sp.
3 chl. 1.5 turns
38 μm diam.
Lake Kizaki
Omachi
Nagano, 2005
Spirogyra sp.
3 chl. 2 turns
35 μm diam.
Ajisai Park
Kodaira
Tokyo, 2006
