Orthotrichum killiasii Müller Hal.; O. speciosum subsp. killiasii (Müller Hal.) Kindberg; O. speciosum var. killiasii (Müller Hal.) Venturi

Plants 0.8-5 cm. Stem leaves loosely erect, usually slightly contorted or curved when dry, lanceolate to narrowly lanceolate, 3-4 mm; margins revolute nearly to apex, entire; apex acuminate to narrowly acute; basal laminal cells elongate, walls thick, nodose or wavy; distal cells 7-13 µm, 1-stratose, papillae 1-3 per cell, conic or 2-fid, large. Specialized asexual reproduction absent. Sexual condition gonioautoicous. Seta 1-3 mm. Capsule exserted to rarely emergent, cylindric to ovate-cylindric when mature, 1.5-2.4 mm, slightly 8-ribbed to mid capsule; stomata superficial; peristome double; prostome absent; exostome teeth 8, , recurved, , coarsely papillose; endostome segments 8, well developed, , of 2 rows of cells, , coarsely papillose. Calyptra conic-oblong, smooth, hairy, hairs finely papillose. Spores 13-26 µm.

Coniferous and deciduous trees, rock; low to high elevations (10-2000 m); Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, P.E.I., Que., Sask., Yukon; Alaska, Calif., Colo., Idaho, Mich., Minn., Mont., Nev., N.H., N.Y., Oreg., Utah, Wash., Wyo.; Europe; n Asia; n Africa.

Orthotrichum speciosum is primarily western and Arctic in distribution; the plants are distinguished by their ribbed capsules, large size, and more slender leaf apices.