Inspection of trees for the presence and extent of decay should be part of any hazard tree analysis in the urban forest. Identification of the fungi responsible for the decay allows prediction of tree performance and informs management decisions. Although trees can contain some amount of decay for many years and continue to contribute to the community landscape, decay can be the basis for tree pruning or removal. Forest Service scientists prepared a series of publications focused on some of the major decay fungi associated with oaks, riparian-associated trees (poplars, box elder, alder, sycamore) and other hardwoods. Articles describe the type of decay, provide descriptions and photographs of fungal fruiting bodies, and discuss the impact of the type of decay on hazard tree analysis. Although targeted towards arborists in the West and Southwest, many of these fungi are ubiquitous throughout North America. The series introduces arborists to the concept of wound-induced discoloration, a condition described as "skeleton decay," through a description and dissection of a unique pattern of decay in eastern redcedar. The series includes recommendations of web resources arborists can use to continue their studies and master the knowledge necessary to prepare accurate hazard analyses.