Hypnum sibiricum Müller Hal., Syn. Musc. Frond. 2: 418. 1851; Myurella careyana Sullivant; M. sibirica var. tenella (Habeeb) H. A. Crum, Steere & L. E. Anderson

Plants green, glaucous. Stem leaves loosely erect to wide-spreading, distant, ovate, 0.4-0.6 mm; margins irregularly dentate to spinose-dentate; apex long-apiculate to slender-acuminate; distal laminal cells strongly 1-papillose abaxially.

Mesic, calcareous rock crevices; low to moderate elevations; B.C., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que., Yukon; Alaska, Ark., Ill., Ind., Iowa, Ky., Maine, Md., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., S.C., Tenn., Vt., Va., W.Va., Wis.; Europe; n Asia.

Myurella sibirica is common in the East but becomes rare in northwestern North America. Small, slender, glaucous plants with widely spaced leaves and very large papillae distinguish this species. The leaves end in a rather long, slender apiculus, and the margins are distinctly and irregularly serrulate. The large central papillae and strongly toothed leaf margins distinguish this species from M. julacea and M. tenerrima.