Zygnema is a genus of freshwater filamentous thalloid alga comprising about 100 species.

[4] A terrestrial species, Z. terrestre, is known from India.

Zygnema grows as a free-floating mass of filaments, although young plants may be found anchored to streambeds with a holdfast.

The filaments form a yellow-green to bright green colored tangled mat, and are composed of elongate barrel-shaped cells, each with two star-shaped (stellate) chloroplasts arrayed along the axis of the cell.

This green algae-related article is a stub.