Plants yellow-green. Stem leaves crowded, imbricate, erect, about 0.3 mm, rounded to ovate, obtuse, occasionally with a tiny apiculus; margins serrulate to subentire; distal laminal cells faintly prorulose.

Calcareous habitats, including seepages, rock crevices, and fens; frequent in boreal and Arctic areas, common in western montane areas with calcareous rocks; Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Conn., Maine, Mass., Mich., Minn., Mont., N.Y., Vt., Wash., Wis., Wyo.; Europe; Asia.

This species is distinguished as the small, worm-like plants, yellow-green in color. The leaves are concave and tightly overlap. It is easily distinguished from the other two species of the genus by obtuse leaves that have at most a tiny apiculus.