Plants to 5 cm high, erect in dark green to blackish tufts. Leaves concave due to the ascending margins, erect spreading when moist but appressed when dry, oblong- to ovate-lanceolate, broadest near the base, with broadly rounded apices, to 4 mm long, about 5: 1. Median laminal cells in very regular rows, isodiametric with rounded lumens, thick walled with small corner thickening, to 12 µm wide, with 1–2 low and inconspicuous papillae on each surface. Basal marginal cells quadrate to short rectangular in a small auriculate cluster, to 15 µm wide, pellucid and smooth. Basal juxtacostal cells smooth, elongate with oblique end-walls, to 4: 1, strongly pitted on lateral walls. Cells on adaxial surface of costa elongate and pitted in 2–3 rows. Margins entire or remotely denticulate-incised to dentate near apex, recurved from base to near the apex. Costa strong, often forked distally, ending within about ten cells of apex, not at all keeled. Costa cross-section semicircular and essentially homogeneous, 5–6 cells thick with the cells strongly pachydermous. Axillary hairs rather thick-walled and rigid, 4–5 cells long with the centrally inserted ones longer than the lateral ones, to 100 µm long, with one basal brown cell, not offset from leaf insertion. Rhizoids to 12 µm in diameter at insertion, sparse and essentially restricted to extreme base of plant, smooth, red-brown, monopodial and regularly branched. Stem cross-section without a central strand, with 3–5 rows of somewhat pachydermous inner corticals and with 1–2 layers of strongly pachydermous, red brown outer cortical cells.
Autoicous with perigonia mostly on separate branches from those with the perichaetia. Perichaetia terminal with bracts not different from the vegetative leaves. Capsule immersed on a yellow to yellow brown, smooth and erect seta which seldom exceeds 1.5 mm in length. Urn pale yellowish, to 1.5 mm long, 1.5–2: 1, erect, sulcate above with eight well defined ribs, lightly strangulate when dry. Operculum straight-rostrate. Annulus well-defined, revoluble. Exothecial cells in cross-section bistratose with only the outer walls of the outer layer strongly thickened. Exothecial cells at capsule mouth not strongly reddened, to 25 µm wide, transversely elongate with rounded lumens in up to 4 rows. Exothecial cells at middle of urn mostly rather thin-walled, shortly rectangular, 2–4: 1, to 20 µm broad, strongly differentiated between ridges and valleys of the sulcate capsule. Stomata cryptoporous and nearly covered by the subsidiary cells, restricted to the base of the urn. Exostome teeth reflexed when dry, initially fused in pairs but later separating, pale to light yellow, to 300 µm long, finely and densely papillose. Endostome segments 8 or 16, unusually thick and rigid for the genus, smooth or with shallow linear furrows, comprised of one or sometimes two rows of cells. Calyptra campanulate and fringed, strongly plicate but essentially without hairs. Spores green, to 15 µm, lightly papillose to almost smooth.
Habitat-- On tree roots and bases, and on siliceous rocks, mostly within flood zone of small rivers and streams, sea level to 1000 m., mostly west of the Cascades and Sierra in western
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