Bryol. Eur. fasc. 52–54. 1853. -- Hypnum reflexum Starke ex Web. & Mohr, Bot. Taschenb. 306, 476. 1807.
Hypnum subtenue James, Proc. Amer. Acad. Sci. Nat. Philadelphia 7: 447. 1856.
Plants loosely matted, green to olivaceous or brownish, regularly once pinnately branched with the branches from the prostrate stem Primary stems to 5 cm long with leaves somewhat larger and more spreading than those on the branches. Branch leaves to 1 mm, about 3: 1, symmetric and straight often with a twisted acumen, not at all concave, not plicate, lanceolate and gradually contracted into the acumen, erect spreading. Margins coarsely serrate from base to apex, somewhat recurved at base but plane above, narrowly decurrent by a 1 cell wide strip which extends nearly to insertion of next lower leaf. Median cells smooth, spinulose and thin-walled, to 8 µm wide, mostly 5–8: 1, not pitted. Basal juxtacostal cells short-rectangular, thin-walled with little pitting. Alar region well-demarcated, present in a large patch about 6 cells broad and about 4 cells up the leaf, with cells isodiametric, to 15 µm broad, thin-walled and pellucid. Marginal cells of alar region little differentiated from more interior cells. Costa percurrent or nearly so, nearly filling the acumen. not much tapered, smooth to obscurely spinose distally. Juvenile leaves strongly incurved, to 100 µm long, ovate-lanceolate, about 2.5: 1, minutely serrulate across the acuminate apex. Axillary hairs persistent, to 65 µm, 2-celled with a single pale brown basal cell, thin-walled throughout with some diameter increase in the distal cell. Rhizoids abundantly produced on prostrate stems, elongate and planar branched, brown to reddish-brown, smooth to minutely verruculose, to 12 µm in diameter, clustered on the abaxial leaf base. Stem cross-section with central strand, a stereome 2–3 cells thick, but without an hyaloderm.
Autoicous. Perigonia bud-like, produced near the perichaetia on prostrate stems and large branches. Perichaetial leaves to 1 mm long, sheathing at base but reflexed to squarrose in the abruptly contracted acumen, ecostate, entire below but serrulate on the awn, without alar differentiation. Seta pale to orange brown, papillose throughout, to 12 mm long, distally geniculate. Capsule brown to reddish brown but blackened with age, inclined to almost erect, lightly arcuate, not distorted or sulcate when dry. Urn to 1 mm, about 2: 1. Exothecial cells isodiametric, in regular rows, to 25 µm wide, thick-walled with lumen: wall ratio 2–4: 1. Stomata present at base of capsule but not on raised pustules, short and vertical pored. Operculum conic, about 1/4 as long as urn. Annulus present, of two rows of thin-walled cells. Exostome inserted at mouth of capsule, very narrowly fused at base, teeth to 400 µm long, lanceolate and obscurely shouldered, about 6: 1, tapering to a very narrow tip, horizontally striate, yellow to yellow-brown. Endostome segments lightly papillose, narrow and perforated on keel, about as long as exostome, with basal membrane about 1/3 of total length of endostome. Cilia 1–3, lightly papillose and appendiculate. Spores finely papillose, 12–15 µm.
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