• May be unicellular, colonial, siphonous (tubular), or multicellular
• Most are flagellated but some are non-motile
• Produce food by photosynthesis (chlorophyl a and c, and carotenoid (orange color)
• Reproduction is highly variable
• Cell walls are made of cellulose and pectin
• Food is stored as starch (pyrenoids)
• Sheet-like body (Thallus)
• Spirogyra (water silk) grow as a unicellular green thread or filament