The Zygnematales (Greek: ζυγός (zygós) and νῆμα (nḗma) (nom.

), νήματος (nḗmatos) (gen.)), also called the Conjugatales,[1] are an order of green algae,[2] comprising several thousand different species in two families.

Most members of both families live in freshwater, and form an important component of the algal scum that grows on or near plants and rocks.

[3] Sexual reproduction in Zygnematales takes place through a process called conjugation.

The cells then meet and fuse to form a zygote, which later undergoes meiosis to produce new filaments.