The familiar field and forest mushrooms are the fruiting structures that arise from such a network. To exploit new habitats fungi have to produce countless millions of spores since very few of these spores will successfully form new colonies. With gilled mushrooms the spores are produced on the surface of the gills. These delicate structures serve to increase the surface area available for the production of spores and are protected by the more robust cap. The presence or absence of a volva and ring are important characteristics used for identifying these types of fungi.
Some species have pores , spines or blunt ridges instead of gills.
However, the reproductive structures of many fungi do not have the characteristic mushroom shape at all and range in size from the giant puffball to the tiny conidiogenous structures of moulds. The Ascomycota produce their spores inside a long cell called an ascus . The Basidiomycota form their spores externally on a club-like cell called a basidium. Fungi play a vital role in nature. Many are saprotrophs, living on dead organic matter such as leaf litter and have an important role in re-cycling.