Unbranched, untapered, blue-green filaments with cells shorter than wide (cf. Phormidium), lacking heterocytes. Filaments occur within a firm sheath, and may glide within them. Short sections of filament (hormogonia) can break out of the sheath.
Lyngbya, Owaka River, X15. Photo: Otago Regional Council & Manaaki WhenuaLyngbya, X400. Photo: Otago Regional Council & Manaaki Whenua