What fungal fruiting body is commonly called a shelf fungus when it grows from tree trunks? The answer is bracket fungus. Bracket fungi form shelf-like or semicircular fruiting bodies that project directly from living or dead wood, often without a conventional stem.
The term describes growth form rather than a single evolutionary group. Many bracket fungi are polypores, whose undersides contain numerous pores or tubes that release spores, but some shelf-shaped fungi belong to other lineages. Their tough, woody or leathery bodies help them persist on tree trunks for months or years.
Most bracket fungi are wood-decay organisms. They may act as parasites on living trees and continue as saprotrophs after the tree dies, breaking down cellulose, hemicellulose, and sometimes lignin. This makes them important recyclers in forest ecosystems, although infections can weaken timber and living trees.
“Polypore,” “shelf fungus,” and “bracket fungus” overlap in everyday use but are not perfect synonyms. A bracket fungus is defined mainly by its projecting form; a polypore is more specifically associated with a pore-bearing underside. Bird’s nest, jelly, and cup fungi have different fruiting-body designs.