Fungi which grow on wood are sometimes called "lignicolous" fungi. But why develop a set of keys limited to fungi utilizing wood as a substrate? After all, being lignicolous does not define a taxonomic category. Lignicolous fungi include ascomycetes and basidiomycetes and a large number of classes and orders within each of these groups. Most of these taxa include both lignicolous and terrestrial species. Rather than taxonomy, the keys focus on the biological activity holding this otherwise disparate group of fungi together: their ability to degrade cellulose and lignin, the major components of wood. This ability is often judged negatively on our part. In fact, the introduction to Illustrated Genera of Wood Decay Fungi by Dr. Fergus states that "This manual has therefore been prepared with the hope that it will fill a definite need, that of the general forester to identify decay fungi. It will also provide an illustrated Key for use in a Forest Pathology Laboratory course." Dr. Fergus indicates that the keys in his manual were based on those used by Dr. L.O. Overholts for use in a course in Forest Pathology. Dr. Fergus' book begins to answer the question posed earlier. One reason you might want a set of keys to wood decay fungi is because these fungi cause economic loss. Forest trees and valuable landscape trees can be infected and rotted by these fungi. Knowing the species growing on a tree can help the forester determine the likely extent of loss. Different species are associated with different amounts of decay in the tree. Additionally, some species are restricted to sapwood and will not affect the merchantable volume of heartwood. Some fungi can decay sound wood, others decay only decaying wood and bark.
But being able to identify lignicolous fungi causing economic loss is only one reason why keys to lignicolous fungi might be useful. In the material below, I briefly describe other important reasons people have to know the species of fungi which are found growing on wood. Wood decay fungi are the preeminant recyclers of wood in ecosystems. Without these fungi, wood would never decay. We would be "up to our eyeballs" in twigs, limbs, and tree trunks. Worse, the valuable nutrients in this wood would be locked up and unavailable for new growth. The species of fungi responsible for decaying the wood of the different species of hardwood and softwood trees is of ecological interest. Wood decay fungi include many sought-after edible species such as Pleurotus ostreatus, Grifola frondosa, and Laetiporus sulphureus.
A set of keys to fungi restricted to growing on wood eases the identification process for people with all of the above interests. Field guides and technical monographs cover all genera and species of a group. The identification process can become tedious for groups with many terrestrial species or when using comprehensive field guides. Furthermore, technical literature is often not available to the general user as it may reside in obscure locations or it may require more technical mycological "know how" than that possessed by the general user.
For any of the activities described above, it is my hope that these keys and pictures, within their limitations, will be found useful to identify many of the fungi found growing on wood.
This page © 2008 by Gary Emberger, Messiah College