22. Schistidium papillosum Culmann in J. Amann et al., Fl. Mouss. Suisse. 2: 386. 1918.
Plants in open tufts or mats, usually olivaceous, often with red, yellow, brown, or orange tones, rarely nearly black. Stems 1-10 cm, central strand indistinct or absent. Leaves erect or curved when dry, ovate-lanceolate, sharply keeled distally, (1.2-)1.6-2.4 mm, 1-stratose, sometimes with 2-stratose striae distally; margins recurved to near apex, often denticulate distally, usually 2-stratose, occasionally in more than one row; apices acute; costa percurrent or excurrent as a denticulate or spinulose, often flexuose, usually non-decurrent awn, abaxial surface papillose; basal marginal cells quadrate or short-rectangular, usually trigonous; distal cells short-rectangular, angular, or ovate, 8-10 µm wide, papillose, sinuose. Sexual condition autoicous. Capsule dark red-brown or brown, short-cylindric, 0.9-1.4(-1.75) mm; exothecial cells isodiametric or short-elongate, thin-walled, sometimes with small trigones; stomata present; peristome patent to erect, twisted, red- or orange-brown, 300-500 µm, papillose, entire or weakly perforated. Spores 10-13 µm, granulose or verruculose.
Capsules mature late spring to early summer. Rock, rarely on tree bark, in mesic habitats; low to high elevations (0-2000 m); Greenland; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Nunavut, Ont., Que., Yukon; Ala., Alaska, Colo., Idaho, Mich., Minn., Mont., N.Y., Oreg., Wash.; Eurasia.
See comments under 5. Schistidium boreale regarding differences among the North American species of the genus with papillose laminal cells.