Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Substrate and ecology: on the same types of rock as ssp. garovaglii; in desert to montane areas dominated by vegetation similar to that for ssp. garovaglii, but absent from cooler and moister areas with pines or firs World distribution: western North America and South America Sonoran distribution: common in northern and central Arizona, 910-2440 m, occasional in southern California, 670-913 m and Baja California and Baja California Sur, 780-1300 m Notes: Lecanora garovaglii subsp. cascadensis differs from the typical subspecies mainly in having yellowish black to blue-black (N+ red) discs (however, in our region, where both subspecies occur primarily in shaded habitats, the discs of both tend to be pale yellow, N-, but sometimes partly blackened by parasites and then N+ reddish). The various differences in thallus anatomy and spore sizes among L. cascadensis, L. nevadensis, and L. garovaglii that were noted by Magnusson (1933, 1940) do not appear to be consistent or useful. Although in practice the two subspecies of L. garovaglii are sometimes very difficult to distinguish from each other (especially without a N test), they do have somewhat different distributions (complete absence of subsp. cascadensis in Eurasia and Africa, and in North America with ssp. cascadensis primarily in the Cascades, Sierra Nevada, and Great Basin, vs. the typical variety apparently restricted to the Rocky Mountains and their foothills, with extensions into northwestern Mexico) helps to justify treating cascadensis as a subspecies. The same set of chemotypes, at least as far as cortical chemistry goes, occur in both subspecies, but in our region, isousnic acid is essentially restricted to ssp. cascadensis.