Most corticioid fungi are wood-rotting species and rely on wood degradation as their primary means of nutrition. Although the fruiting bodies are formed on the underside of dead branches or logs, the fungus resides within the wood. A number of species are litter-rotting and produce fruitbodies underneath fallen leaves and compacted litter as well as on fallen wood. Some of these species are known to be ectomycorrhizal (forming a beneficial association with the roots of living trees). A few specialist species grow on dead herbaceous stems and leaves or on dead grass, rush, and sedge stems, especially in marshes. Parasites of plants and other fungi are also found in the group.
Corticioid fungi have a worldwide distribution, but are obviously commonest in forest communities.