Bryum fulvellum Dickson, Fasc. Fl. Crypt. Brit. 4: 10, plate 11, fig. 1. 1801; Dicranum fulvellum Smith

Plants small, in compact, moderately shiny, yellow-brown or green tufts. Stems (0.5-)1-2(-4) cm. Leaves erect or falcate-secund, lanceolate, subulate, 2-3 mm; costa 30-60 µm wide at base, very long-excurrent, rough near tip; distal laminal cells mostly rectangular (2-5:1), incrassate; basal laminal cells elongate, alar cells differentiated. Seta long, (3-)4-6(-7) mm. Capsule exserted, slightly curved, obscurely to distinctly ribbed when dry, annulus of 2 rows of cells; peristome red, spreading outward when dry. Spores 16-28 µm.

Capsules mature summer. Siliceous rock or soil; moderate to high elevations; Greenland; Alta, B.C, N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S. Que, Yukon; Alaska, Idaho, Maine, Mont., N.H., N.Y., Oreg., Wash.; Europe; Asia.

Arctoa fulvella occurs frequently on mountain summits and exposed ledges, and is often found in late snowbed communities with Kiaeria falcata. Superficially it resembles Blindia acuta, which is distinguished by enlarged, orange alar cells and dark brown peristome teeth that do not flare conspicuously outward. Dicranella heteromalla vegetatively resembles A. fulvella, but its inclined capsules and boreal rather than alpine habitat will separate them. The long-excurrent costa distinguishes this species from other Arctoa species.