Polypore

Polypores, also called bracket or shelf fungi, are a morphological group of basidiomycete-like gilled mushrooms and hydnoid fungi that form large fruiting bodies called conks, which are typically woody, circular, shelf- or bracket-shaped, with pores or tubes on the underside.

Conks lie in a close planar grouping of separate or interconnected horizontal rows. Brackets can range from only a single row of a few caps, to dozens of rows of caps that can weigh several hundred pounds. They are mainly found on trees (living and dead) and coarse woody debris, and may resemble mushrooms. Some form annual fruiting bodies while others are perennial and grow larger year after year. Bracket fungi are typically tough and sturdy and produce their spores, called basidiospores, within the pores that typically make up the undersurface.

Most polypores inhabit tree trunks or branches consuming the wood, but some soil-inhabiting species form mycorrhiza with trees. Polypores and the related corticioid fungi are the most important agents of wood decay, playing a very significant role in nutrient cycling and aiding carbon dioxide absorption by forest ecosystems. Several polypore species are serious pathogens of plantation trees and are major causes of timber spoilage.

As polypores are much more diverse in old natural forests with abundant dead wood than in younger managed forests or plantations, a number of species have declined drastically and are under threat of extinction due to logging and deforestation. Polypores are used in traditional medicine, and they are actively studied for various industrial applications.

Because bracket fungi are defined by their growth form rather than phylogeny, the group contains members of multiple clades. The beefsteak fungus, a well-known bracket fungus, is actually a member of the agarics. Other examples of bracket fungi include chicken of the woods (or sulphur shelf), birch bracket, dryad's saddle, artist's conk, and turkey tail.^{[citation needed]} The name polypores is often used for a group that includes many of the hard or leathery fungi, which often lack a stipe, growing straight out of wood. "Polypore" is derived from the Greek words poly, meaning "much" or "many", and poros, meaning "pore".

For most of 20th century polypores were treated as a family, the Polyporaceae. Reconstructions of family trees of fungi show that the poroid fruiting body has evolved numerous times in the past. Modern DNA-based evolutionary classification places polypores to at least 12 orders. The orders containing most polypore species are the Polyporales (genera such as Fomes, Polyporus and Trametes) and Hymenochaetales (e.g. Oxyporus, Phellinus and Trichaptum). Economically perhaps the most significant polypores Heterobasidion spp., pests of conifer plantations, belong to the Russulales. Other polypore orders are the Agaricales, Amylocorticiales, Auriculariales, Boletales, Cantharellales, Gloeophyllales, Sebacinales, Thelephorales and Trechisporales.

The Polyporales in the modern sense are not only polypores but also other fruiting body types such as crust fungi, hydnoid fungi and agaricoid mushrooms.

Currently polypores are divided into about 170 genera.