Zygnema is a genus of freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 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 chloroplast

Chloroplast

Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...

s arrayed one after the other 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