Poelt, J/ Nash, TH, III 1993: Studies in the Umbilicaria vellea group (Umbilicariaceae) in North America. - The Bryologist96(3): 422-430. [RLL List # 153 / Rec.# 14752] Keywords: NORTH AMERICA/ UMBILICARIA
Abstract: 9 fig. [New: Umbilicaria americana sp. nov. This new species is segregated from the North American representation of U. vellea. Taxonomic notes on seven other similar species are also provided, along with a key for all nine species.]