information:filtering
Fundamental elements

The diagram above shows the fundamental elements of the alternation of generations in plants. There are many variations in different groups of plants. The processes involved are as follows:

The 'alternation of generations' in the life cycle is thus between a diploid (2 n) generation of multicellular sporophytes and a haploid (n) generation of multicellular gametophytes.

The situation is quite different from that in animals, where the fundamental process is that a multicellular diploid (2 n) individual directly produces haploid (n) gametes by meiosis. In animals, spores (i.e. haploid cells which are able to undergo mitosis) are not produced, so there is no asexual multicellular generation. Some insects have haploid males that develop from unfertilized eggs, but the females are all diploid.