This rating reflects the likelihood of encountering any individual species on an urban tree. Several species can be found in most areas of the country and are extremely common on urban trees. Other species may be more common in some geographic areas are relatively rare in others, reflecting host distribution and/or climatic ranges. Some species seem to be relatively rare in urban environments but are relatively common in forest habitats.
Very common species that those that are encountered almost every year and typically have a wide host range and can be found on hosts that are common in urban environments (for example Norway maple and honeylocust) (Photograph 1). They are mostly annual species but also include a couple of perennial species that are likely to be found fruiting when the host is encountered.
These are the annual fungi that are often found on urban trees but may have more restricted host ranges or fruit less commonly on an annual basis. Several perennial species fall into this category because of their perennial nature, relatively wide host range, and frequent appearance on urban tree species.
This category is for species that are less common on urban trees because of host restrictions or an apparent preference for forested habitats. Some are relatively common in woodlands are seldom found on urban trees.
Some wood decay species are rare on urban trees and are relatively rare even in forested habitats. It would be unusual to find the species in this category on an urban tree.