Each haploid nucleus of a mushroom has 9 chromosomes.

A fungus has a mycelium of hyphae: septate (with cross walls) or coenocytic (no cross walls, many nuclei). The wall is of chitin and polysaccharides. Fungi are saprophytes, parasites or symbionts (lichens, mycorrhiza). Sexual reproduction: plasmogamy (two cells fuse, $n + n$), karyogamy (the nuclei fuse, $2n$), then meiosis (haploid spores, $n$).