Zygnema

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.

Zygnema
Zygnema, showing characteristic dual star-shaped chloroplasts. Numbered ticks are 20 μm apart.
Numbered ticks are 122 μm apart.
Scientific classification
Kingdom:	Plantae
Class:	Zygnematophyceae
Order:	Zygnematales
Family:	Zygnemataceae
Genus:	Zygnema C. Agardh, 1817
Synonyms
Globulina Link in Nees 1820[1] Lucernaria Roussel, 1806[2][1] Pleurodiscus Lagerheim, 1895[3][1] Rhynchonema Kützing, 1849[1] Stellulina Link, 1833[1] Thwaitesia Montagne, 1845[1] Tyndaridea Bory de Saint-Vincent 1822[1] Tendaridea Bory de Saint-Vincent 1822[1] Tendaridella Gaillon, 1833[1]

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