15. Schistidium frisvollianum H. H. Blom, Bryophyt. Biblioth. 49: 87, fig. 25. 1996.
Plants in cushions or tufts, orange-brown or olivaceous. Stems 0.5-2(-3.5) cm, central strand distinct. Leaves erect or slightly curved when dry, ovate-lanceolate to ovate-triangular, sharply keeled distally, 1.3-2.4 mm, 1-stratose; margins usually recurved to apex, often sharply denticulate distally, 1-stratose or 2-stratose; apices acute; costa excurrent as a coarsely denticulate, usually decurrent, straight or flexuose awn, rarely percurrent, abaxial surface of the awn usually papillose; basal marginal cells rectangular, quadrate, or ovate; distal laminal cells quadrate or short-rectangular, 8-11 µm wide, papillose, strongly sinuose often with pale yellowish walls. Sexual condition autoicous. Capsule orange-brown or yellow when old, sometimes red-brown, ovoid-cylindric, 0.65-1.1 mm, occasionally striate; exothecial cells isodiametric or oblate, often somewhat angular, thin-walled; stomata present; peristome patent revolute, 220-330 µm, red, densely papillose, usually weakly perforated. Spores 8-11 µm, granulose or nearly smooth.
Capsules mature late spring to early summer. Fissures, limestone and dolomites in Arctic fellfields, polygon fields, and on dry ridges in tundra; low to moderate elevations (0-300 m); N.W.T., Nunavut, Yukon; Alaska; Eurasia.
Schistidium frisvollianum is the most ornamented species of the genus in the flora area. Its strongly papillose lamina, decurrent and usually spiny-denticulate awns, and denticulate leaf margins combine with its distinctive orange-brown color to make it an easily recognizable taxon. See the comments under 5. Schistidium boreale regarding differences among the North American species of Schistidium with papillose laminal cells.