Definition of Gametophyte
The gametophyte is the generation of plants which is haploid. In this phase, the male and the female organs are developed and eggs and sperms are produced by these organs through the process of simple mitosis. Now, the plant gets ready for sexual reproduction. When the egg and the sperm are fused during the process of fertilization, a zygote is formed. This zygote then develops into a diploid generation which is termed as the sporophyte.
During this phase, the unicellular spores are produced through the process of meiosis. These spores are then developed into a new gametophyte generation. This phenomenon is known as alternation of generations. The gametophyte phase is dominant in the plants which are non-vascular whereas the sporophyte phase is dominant in vascular plants.