Hypnum fauriei Cardot, Beih. Bot. Centralbl. 17: 41. 1904.
Plants creeping, medium-sized, 4--8 cm, ca. 0.13 cm broad including leaves, yellowish brown to brownish green, somewhat glossy, often densely branched, regularly to irregularly pinnate, often attached to substratum by numerous rhizoids; branches up 1 cm, ca. 0.08 cm wide (with leaves). Stems lacking hyalodermis, reddish to yellowish; pseudoparaphyllia foliose, triangular to lanceolate. Leaves of stem falcate to circinate, from broadly ovate base, tapering to a slender acumen and narrowing to insertion, sometimes weakly cordate, 1.4(--2.2) × 0.4(--0.75) mm, yellowish brown at base, margin crenate to entire or toothed in acumen, proximal margin excavate in alar portions where the cells are often colored, hyaline and few (1--3), rectangular to quadrate and often bulging with 2 or 3 subquadrate to rectangular cells distally, sometimes with rectangular decurrent cells at insertion; median laminal cells linear to slightly vermicular, 50--70(--80) × 3--5 µm, basal cells shorter and thicker with thicker porose walls. Sexual condition autoicous. Seta 3--4 cm, reddish brown or yellowish brown. Capsule inclined to horizontal, cylindric, 2--3 × 0.9--1 mm, curved, brown when mature, operculum conic-apiculate, annulus 3-seriate, cilia of endostome 2--3, endostome segments with large perforations.
Capsules mature summer (July). Tree bases, stumps, rotten logs, occasionally on humus and rock, mixed forest; 0--2000 m, lower elevations in the northern part of the range but at higher elevations in the mountains southwards; N.B., N.S., Ont., Que.; Ga., Maine, Mich., Minn., N.H., N.Y., N.C., Pa., Tenn., Vt., Va., W.Va.; E Asia: Korea, Japan, Russia (Altai).
Hypnum fauriei has posed difficulties since its early report from North America as H. fertile, a species restricted to Europe. It appears to be uncommon, but superficial examination could allow misidentification as H. imponens or even H. plicatulum. The larger number of alar cells that are often delimited by colored cells nearby easily distinguish H. imponens from H. fauriei; the broad, foliose, much-toothed pseudoparaphyllia that are usually frequent in H. imponens differ markedly from the triangular to lanceolate pseudoparaphyllia occasionally found in H. fauriei. In addition, the erect rather than inclined capsules also immediately separate H. imponens. Hypnum plicatulum has few alar cells, but the leaf bases are somewhat to strongly auriculate, the plants are yellow-green, and the hyalodermous stem cells are apparent, all features lacking in H. fauriei.