Stereodon bambergeri (Schimper) Lindberg
Plants robust, 2--8(--10) cm, ascending to prostrate, reddish to yellowish brown, shiny, usually little and irregularly branched, but occasionally pinnately branched, with branches of variable length 0.2--0.6 cm, leafy stems 0.1--0.2 cm broad. Stems dark brown to reddish brown, with weak central strand; pseudoparaphylla wide, foliose. Leaves of stem leaves falcate to circinate-secund, oblong-ovate to oblong-lanceolate, narrowed to a slender acumen, margins plane and sinuate to weakly serrate, 1.5--2 × 0.4--0.6 mm, curving gradually to alar cells, or forming a weak auricle just above the alar cells; costa single or double, and unequal, short to long, unequal; median cells 30--60 × 35--6 µm, somewhat to markedly pitted, cells of leaf base shorter and more strongly pitted, pigmented yellow to orange; alar cells in a well-defined, weakly to markedly excavate brownish group 3--7 cells high along margin and extending to 3--6 cells wide, quadrate to short-rectangular. Sexual condition dioicous; inner perichaetial leaves erect, ovate to oblong-lanceolate, abruptly narrowed to a slender entire acumen, laciniate at shoulders, plicate. Seta reddish brown, 1.3--2 cm. Capsule yellowish brown, inclined to horizontal, 1.3--1.5 mm, excluding the conic operculum, cilia of endostome 2--3
Sporophytes infrequent, capsules mature summer (July, August). Often in seepage habitats, also in dry tundra, open conifer forest, mainly calcicolous; 0--2500 m; Greenland; Alta., B.C., Man., Nfld., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Mont.; Europe; Asia.
Hypnum bambergeri is widely distributed in the Arctic and extends southward, especially in alpine sites. This species superficially resembles Limprichtia, from which it is readily separated by the single rather than double costa found in the latter genus, and also by the well-defined alar cells of H. bambergeri, absent in Limprichtia. The leaf cells pitted throughout separate this species from all others in Hypnum. The usually calcareous terrestrial seepage habitat is also a useful trait.