Zygnema

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

Species
Some species include:
 * Z. atrocoeruleum
 * Z. binuclearioides
 * Z. carinthiacum
 * Z. carteri
 * Z. circumcarinatum
 * Z. coeruleum
 * Z. conspicuum
 * Z. cruciatum
 * Z. cyanosphaeroidicum
 * Z. cylindricum
 * Z. cylindrospermum
 * Z. fanicum
 * Z. gorakhporense
 * Z. insigne
 * Z. kashmirense
 * Z. kiangsiense
 * Z. leiospermum
 * Z. melanosporum
 * Z. momoniense
 * Z. normanii
 * Z. oveidanum
 * Z. pectinatum
 * Z. peliosporum
 * Z. quadrispirale
 * Z. ralfsii
 * Z. rivulare
 * Z. ruviatum
 * Z. schwabei
 * Z. spontaneum
 * Z. stagnale
 * Z. stellinum
 * Z. subtile
 * Z. tenue
 * Z. tenuissimum
 * Z. terrestre
 * Z. vaginatum
 * Z. vaucherii
 * Z. verrucosum