Zygnemeae Kützing, 1843 The Zygnemataceae are a family[2] of filamentous or unicellular, uniseriate (unbranched) green algae.

The family is notable for its diversely shaped chloroplasts, such as stellate in Zygnema, helical in Spirogyra, and flat in Mougeotia.

Classification and identification is primarily by the morphology of the conjugation, which is somewhat rare to find in natural populations of permanent water bodies; when in the vegetative state, the rarer genera resemble the three most common, and are often mistaken for them and catalogued as such.

Species typically exist as floating mats in stagnant water in ditches and ponds, but some also grow in moving water, attaching themselves to a substrate by rhizoid-like projections of the basal cells of the filament.

[4] Most genera (all except Mesotanium and Spirotaenia) previously assigned to Mesotaeniaceae as well as the Desmidiales actually emerged in the Zygnematacae.