Monograph of the Lichen Family Umbilicariaceae in the Western Hemisphere: 42 (1950).

Basionym: Umbilicaria pensylvanica Hoffm., Descr. Adumb. Plant. Lich. 3(no. 4): 5 (1801).

Note: The species is sometimes spelled "pennsylvanica", but the original spelling in Hoffmann (1801: 71 and Tab. LXIX) is "pensylvania" which has to be followed. Acharius also writes it "pensylvanica". The state of Pennsylvania is of course named after its founder William Penn, but apparently it was not uncommon to write it "Pensylvania" all the way up to the 20th century (G. Hestmark by email).