Surface area and reproduction
Most fungi have a very specialized niche in the environment. Since they can’t move, they must use their spores to get to a new niche
the chance of any single spore landing on a substrate it can exploit are very small
thus, fruiting bodies must produce as many spores as possible so that a few of them will, by chance, be successful
Fungi have a great variety of ways of increasing the spore-bearing surface (hymenophore) area of their fruiting bodies
Notes:
Surface area for bearing spores is an important concept in understanding the reproduction in Ascomycota and Basidiomycota.