parts of a filament

trichome

the cell row itself

sheath

mucilaginous coating of cell wall (polysaccharides & polypeptides)

microcystis

genus where each cell is not covered in a sheath, but scattered in a gelatinous matrix

anabaena

genus with one trichome per sheath

cylindrospermum

genus

• trichomes have an equal diameter throughout their length

• sheath is nearly invisible

lyngbya

genus

• trichome that lacks heterocysts

• trichome has an equal diameter through the whole length

• single trichome in a rigid sheath

• thick, prominent mucilaginous sheath

tolypothrix

genus

• false branching that occurs when a trichome breaks and a fragment continues to grow past it

stigonema

genus

• sheath very prominent