Brachythecium albicans (Hedw.) B.S.G.
Plants in loose to rather compact mats, pale yellowish to whitish-green, often with a russet cast. Stems to 10 cm long, prostrate to ascending, irregularly branched, so terete foliate as to appear somewhat julaceous, often with the branches so parallel as to appear combed. Leaves appressed to strongly ascending, to 2.5 mm, 3–4: 1, symmetric to slightly falcate, lanceolate to ovate-lanceolate, lightly plicate at least on stems, long acuminate with the acumens straight and parallel when moist but flexuose when dry. Margins plane, moderately to strongly decurrent on stem leaves but less so on branch leaves, mostly entire on acumen but usually with some serrulations on shoulder. Median cells smooth, to 8 µm wide, long rhomboidal to linear, 6–15: 1, rather thin-walled, not pitted. Alar cells quadrate to short oblong with walls not strongly thickened, only gradually differentiated from adjacent laminal cells. Apical cells elongated, not differentiated. Costa extending 1/2–3/4, without an abaxial spine. Pseudoparaphyllia deltoid to orbicular, strongly overarching the bud. Axillary hairs of 3 similar cells, to 100 µm with no basal brown cells, not offset from leaf insertion. Rhizoids red-brown, 12–14 µm, smooth, in scattered fascicles on ventral portion of prostrate stem.
Dioicous with male plants similar to females. Perichaetial bracts costate, abruptly acuminate from a ligulate-lanceolate base, cells uniformly long and straight to 10: 1. Seta yellow- to red-brown, smooth, to 2 cm long. Capsule brown to dark brown, inclined to horizontal, strangulate when dry. Urn to 1.5 mm, oblong and asymmetric, 2–3:1. Exothecial cells in regular vertical rows, to 20 µm wide, mostly 2: 1 but some to 4: 1, with moderately thick, red-brown walls and with stomata restricted to neck. Operculum conic to short-rostrate, about 1/4 as long as urn. Annulus differentiated, not revoluble. Exostome to 500 µm long, horizontally striate below, papillose above, yellow- to red-brown. Endostome segments low papillose, open on keel, about as long as exostome with basal membrane about equal in length to the segments. Cilia 2–3, nodose. Spores finely papillose, to 15 µm.
This is one of the most easily recognized of California Brachytheciums. No other local costate, plicate leaved pleurocarp has such whitish, almost julaceous stems and leaves with long, essentially entire acumens. The almost combed appearance of the parallel branches is a good diagnostic character when that feature is present.
| Literature | Bradshaw 1926; Flowers 1973; Harthill et al. 1979; Holmberg 1969; Howe 1896; Ireland 1982; Kellman 2003; Koch 1950a, 1951e, 1958; Koch and Ikenberry 1954; Lawton 1971; McCleary 1972; McGrew 1976; Showers 1982; Spjut 1971; Strid 1974; Thomson and Ketchledge 1958; Toren 1977; Whittemore and Sommers 1999; Yurky 1995. |
| Illustrations | Malcolm et al. 2009 p. 259; Abramov and Volkova 1998; Flowers 1973; Ireland 1982; Lawton 1971; Sharp et al. 1994; Smith 1978. |
| Bioregions | CaR, CW, NW, SN. |
| Vouchers | Fresno Co.: Grizzly Falls along Highway 180, South Fork Kings River, Sequoia National Forest, Shevock 12438; Lake Co.; Upper Nye Camp Site just north of Snow Mountain Wilderness boundary, Mendocino National Forest, Shevock, Bourell, & Toren 15841; San Mateo Co.: Big Canyon Park at Brittan Avenue just east of Crestview, San Carlos, Whittemore 4295 (UC); Trinity Co.: Hall City Caves east of Wildwood, Shasta-Trinity National Forest, Norris 71687. |
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