Organisms which reproduce by:

(i) Budding: Hydra and Yeast.
(ii) Fragmentation: Spirogyra and flatworm.
(iii) Spore formation: Bacteria, Mucor, Fern of Moss.

Reproductive process is not essential for an individual. But it is very necessary for the continuity of the species. Reproduction performs following functions:
(i) In the process of reproduction one generation of living organisms produces the next generation i.e., parents produce offspring like themselves. Thus, this process preserves a species and maintains continuity of the race.
(ii) Reproduction is also the means of increasing the population of a species.
(iii) Reproduction plays an important role in evolution by transmitting favourable variation from parents to offspring.