Reproduction in Spirogyra : Two types of reproduction seen in Spirogyra :
(a) Vegetative reproduction : If the filaments of Spirogyra is broken into pieces, each piece is then capable of developing into a new filament.
(b) Sexual reproduction: It takes place by two methods:
(i) Scalariform conjugation: (a) It takes place when two filaments come to lie parallel to each other.
(b) In both the filaments tubular outgrowth appears which increase in length and touch each other. These tubes are called conjugation tubes.
(c) The contents of the cells contract and loose water to become round. These are called as gametes but the 1 cells are similar to each other in all respects.
(d) The end partition walls of the conjugation tubes dissolve. As a result an open conjugation tube is formed.
(e) The gamete of male filament now creep to the i conjugation tube in the female filament and fuse to form zygospore.
(f) It becomes brown and then black acquiring a resistant wall.
(g) After some time a short tube appears in the zygospore. It divides transversely and develop into a filament.
(ii(Lateral conjugation : (a) This takes place between the cells of the same filament. Here the conjugation tube is formed on one side of the partition wall.
(b) The gametes are formed in the same way as described above.
(c) Gamete of one cell passes into the other cell through the tube and fuse with the stationary gametes to form in the same way as described above.
(d) In the conjugation gametes of alternate cells move to the adjacent cell.