Plants erect in green to brownish green wefts, to 2.5 cm high. Leaves not much keeled, lanceolate to rather narrowly lanceolate with acute apices, to 1.5 mm long, about 2.5–3.5: 1, erect to imbricate when moist, little changed upon drying, not plicate. Median laminal cells rhomboidal with walls rather thick (lumen: wall ratio 5–6: 1) 3–5: 1, smooth throughout or usually with some of the distal cells slightly prorate abaxially, not pitted, to 12 µm wide. Basal and alar cells shorter and and slightly broader than median cells, often with a few nearly isodiametric. Cells near apex short elliptic 2–3: 1, typically somewhat distally prorate with these prorate cells also covering the distal portion of the costa. Marginal decurrency in a short strip to 3 cells long and 3 cells wide distally. Margins plane or nearly so except at the slightly recurved extreme leaf base, serrulate with pachydentate teeth oriented out of the plane of the leaf lamina. Limbidium not clearly demarcated, unistratose throughout. Costa filling about 1/5 of leaf base, somewhat tapering above, green to red-brown, ending in the bluntly acute leaf apex. Costa cross-section with a strong dorsal and ventral epidermis, with a well-demarcated single layer of guide cells but with only an abaxial stereid band. Axillary hairs 4–5 cells long, to 60 µm, with 1–2 basal brown cells and with 3 more distal, somewhat inflated and thin-walled terminal cells. Rhizoids to 15 µm wide at insertion, densely papillose, dark brown to red-brown, sparingly branched, surrounding an isodiametric macronematal area to 100 µm wide. Stem cross-section elliptic, with an inconspicuous central strand, with the hyaline and leptodermous inner corticals abruptly transitting to a single layer of only moderately pachydermous, red brown outer cortical cells, without a hyaloderm. Gemmae absent.
Paroicous with perigonia placed very near the perichaetia. Perichaetial leaves markedly larger than vegetative leaves, to 5 mm long with bracts lanceolate, 4–6: 1, remotely serrulate with blunt teeth and with the cells near the leaf apex somewhat prorate. Seta lustreless pale-brown to yellow-brown, smooth, erect but sharply geniculate distally, to 25 mm long. Urn to 2.2 mm long, short-cylindric, 2–2.5: 1, pendent or nearly so, neither sulcate nor strumose. Operculum conic to conic-apiculate. Annulus revoluble, of 2–3 rows of very thick-walled cells. Exothecial cells at capsule mouth to 20 µm broad, transversely elongate (about 2: 1) in one or two rows. Exothecial cells at middle of urn rectangular with lateral walls curved and thin, 2–3: 1, to 40 µm broad, in regular rows, with walls thin (lumen: wall ratio >10: 1. Stomates phaneroporous and vertical, restricted to neck of capsule, not raised on short pustules, somewhat longer than broad. Exostome inserted somewhat below capsule mouth, yellow-brown, to 4050 µm long, inconspicuously shouldered, finely papillose with dorsal lamellae low. Endostome with basal membrane constituting about 1/2 of total length. Segments papillose, about as long as exostome, broadly perforated along center line but almost not keeled. Cilia 1–2, nodose or unappendaged. Calyptra cucullate and smooth. Spores to 20 µm, coarsely papillose.
|Literature||Bradshaw 1926; Crum and Anderson 1981; Flowers 1973; Harpel 1980a; Harthill et al. 1979; Kellman 2003; Kingman 1912; Koch 1950a, Koch and Ikenberry 1954; Lawton 1971; McGrew 1976; Shaw 1982; Shevock and Toren 2001; Showers 1982; Spjut 1971; Strid 1974; Yurky 1990, 1995. As Bryum nutans var. bicolor Lesquereux 1868; Watson 1880.|
|Illustrations||Abramov and Volkova 1998. Crum and Anderson 1981; Flowers 1973; Ignatov and Ignatova 2003; Ireland 1982; Lawton 1971; Ochyra 1998a; Sharp et al. 1994; Shaw 1982; Smith 1978.|
|Bioregions||CaR, CW, NW, SN, SNE.|
|Vouchers||Alameda Co.: near Claremont Hotel, Berkeley, Morse 26 (UC) [determined by Shaw]; Fresno Co.: between Crown Creek and Blue Canyon, Kings Canyon National Park, Shevock & York 14142 (determined by Shaw); Lake Co.: south shore of Clear Lake at Sulfur Bank Mine, Toren & Dearing 7278 (CAS); Mendocino Co.: Pgymy Cypress Forest along Summers Lane near Highway 20 and Fort Bragg, Norris 11768; Mono Co.: near Lake Mary, Mammoth Lakes region, Inyo National Forest, Shevock & Nelson 13787 (determined by Shaw); Nevada Co.: Sagehen Creek Biological Station, Tahoe National Forest, Tavares 1963 (UC) [determined by Shaw]; Siskiyou Co.: trail to Paradise Lake about 1 mile from Marble Valley Guard Station, Spjut 1140 (UC); Tulare Co.: Slate Mountain Botanical Area, Sequoia National Forest, Shevock 15680 (determined by Shaw). |