Xanthoria parietina in the Inland Pacific Northwest

The lichen Xanthoria parietina has a widespread distribution in Asia, Africa, Australia, and Northern Europe.  Records of this species in the United States have been limited to coastal areas, hence its common name, “the maritime sunburst lichen” (Brodo et. al., 2007).  Xanthoria parietina has thus far only been reported once in an inland area in the Pacific Northwest: in Montana (McCune et al., 2014).  Here, we report X. parietina in additional inland cities in Idaho (Moscow, Coeur d’Alene, and Boise) and Washington (Pullman and Spokane).  Our hypothesis that X. parietina was introduced to these inland cities on woody plants shipped from coastal nurseries was supported by the following findings: 1) it was found on stock available for sale in an Oregon coastal nursery; 2) in Moscow it was most common in the UI Arboretum in which coastal nursery stock is commonly planted; and 3) it was not found on naturally occurring woody plants in natural areas outside of Moscow.  It is important to know where X. parietina occurs because it might eventually decrease native lichen diversity through displacement of local species (Gadson et. al., 2010).