Zygnema
Like Spirogyra and Mougeotia, Zygnema reproduces through both scalariform and lateral conjugation.   During scalariform conjugation, a pair of filaments aligns themselves laterally and connects via branch-like conjugation tubes. This tube grows from each filament and meets in the middle to form an enclosed space for the gametes to move, combine, and develop into resistant-walled zygotes. Each zygote will grow into a single filament.   Lateral conjugation occurs when gametes produced by adjacent cells on the same filament meet and develop within a short, curved conjugation tube. During conjugation, the filaments change from bright green to brownish in color.   Rarely, Zygnema reproduces asexually to form thick-walled akinetes. These resting cells are filled with stored oils and starch and can survive for over a year before germinating into new filaments.