Spirogyra is often called as the pond-scum because of the slippery feel of the threads. It is a free living green alga that usually occurs floating in standing water in the form of bright, green, silky masses slimy to touch. All the cells in the filament are similar in structure, function and are independent of each other. There is thus neither any differentiation of cells in the filament nor any division of labour. The basal cell in these species functions as an attaching organ. It develops rhizoidal outgrowths which assist in attaching the filament to the substratum. Asexual reproduction takes place by the formation of any kind of asexual spores is normally lacking. Sexual reproduction is isogamous and accomplished by the method of conjugation which may be scalariform or lateral.