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Spirogyra is without doubt the best known of all the Green algae. It is a very large genus with very wide distribution. It is common in the Cheney area and is easily found in streams, vernal pools and lakes in the area. Ease of recognition is due to the presence of one or more spirally arranged, ribbon-like chloroplasts that extend the length of each cell. Life Cycle The life cycle of Spirogyra is extremely simple and is described below under "sexual reproduction". ASEXUAL REPRODUCTION Asexual reproduction in Spirogyra is generally by fragmentation. SEXUAL REPRODUCTION Sexual reproduction in Spirogyra is isogamous via a process first described as conjugation. There are a couple of different patterns of conjugation, one involving adjacent cells in a singe filament and the other involving conjugation between cells in two filaments. The latter process is described here. In this process, a number of filaments may aggregate in a gelatinous matrix. Papillae develop on the walls of adjacent cells (sides facing one another). These papillae continue to elongate and ultimately meet and fuse forming "conjugation tubes." After completion of the tubes, the protoplast of the cells of the "donor" filament ("male") will move through the tubes and fuse with the protoplasts of the receiver filament ("female"). The old vegetative cells serve both as the gametangia and gametes in this organism. After fusion, the zygotes develop a thick wall and become a resting stage for the organism.

Spirogyra Under A Light Microscope

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