It is commonly known as summer alga or “hair of princess” or “pond silk” or “water silk” or “pond scum” (due to mucilage covering found in stagnant water).
Cell wall is two layered; outer wall of pectose (water soluble which forms mucilage) and inner wall of cellulose. Primordial utricle is present as thin peripheral cytoplasm due to large central vacuole. Presence of 1-16 ribbon shaped, spiral thloroplast. Coiling is sinistral or left handed. Many pyrenoids are present.
S.adnata, S.jogensis remain attached to substratum by basal cell called holdfast or hapteron.
- Vegetative reproduction: By fragmentation
- Asexual reproduction – It is generally absent except following:
- By parthenospores or azygosporese.g, Spirogyra varians, if placed in sugar solution, develop oarthenospores.
- By akinetes :- e.g., S. farlowi
- By aplanospores
- Sexual reproduction: It occurs by conjugation. It is physiological. anisogamous type.
Type of conjugation
- Scalariform conjugation: Most common type, occurs in heterothallic and homothallic species. Minimum two filaments are involved e.g., Sttuwensis.
- Lateral conjugation: Two adjacent cells of same filament function as gametangia. It is primitive type and uncommon.
- Direct lateral conjugation : e.g. S.jogensis
- Indirect lateral conjugation: e.g. S.affinis