Sexual reproduction in Spirogyra takes place by the process of conjugation. In Spirogyra, the process of conjugation may be of two types - scalariform conjugation and lateral conjugation. Scalariform conjugation occurs in heterothallic species. Lateral conjugation occurs between the adjacent cells of the same filament of homothallic species of Spirogyra. Lateral conjugation are of two types. They are indirect lateral conjugation (chain type) and direct lateral conjugation.