Sciuro-hypnum glaciale (Bruch, Schimp. & Gümbel) Ignatov & Huttunen,  Brachythecium brandegei (Austin) H. Rob. and B. erythrorrhizon var. alpinum Kosovich-Anderson & Ignatov var. nov. (Brachytheciaceae) are reported from the upper elevations of Wyoming’s Beartooth Plateau, Rocky Mountains, U.S.A. All three are rare in North America and are restricted to the most northern and/or alpine habitats. Sciuro-hypnum glaciale is a novelty for continental North America, with the nearest known localities being in Greenland, approximately 4400 kilometers from the Wyoming site. Brachythecium brandegei is a species formerly considered a highly localized endemic of mountainous Colorado. The Wyoming collections constitute the northernmost occurrence reported for North America and extend the known range northward by approximately 700 kilometers. Brachythecium erythrorrhizon var. alpinum is a new taxon described from alpine tundra of the Plateau. Taxonomic issues on the B. erythrorrhizon Bruch, Schimp. & Gümbel, B. brandegei and B. coruscum I. Hagen complex are discussed.