Schistidium cinclidodonteum, Lindbergia 6: 108. 1980. -- Grimmia cinclidontea C. Muell. in Roell., Bot. Centralbl. 44: 387. 1890. -- Schistidium pacificum (Lawton) Ochyra, Fragm. Florist. Geobot. 43: 106. 1998. -- Grimmia pacifica Lawton, The Bryologist 82: 276–280.

   Plants to 3 cm high, in brownish-green to somewhat reddened cushions, opaque-green to blackish below. Leaves lightly imbricate when dry, erect-spreading when moist, falcate and secund on the somewhat hamate stem apices, somewhat concave but not at all keeled, to 3 mm long without an awn, linear lanceolate and subulate distally, 5–8: 1. Median leaf cells in very regular longitudinal rows, bistratose throughout without additional marginal thickening, smooth, to 10 µm wide, isodiametric to short elliptic, 1–1.5: 1, with lumens regular and with distinct corner thickenings. Marginal cells regularly quadrate to short elliptic with rather thick walls but without transverse walls thickening. Basal juxtacostal cells elongate-rectangular and thick-walled with lumen: wall ratio about 1.5–2: 1, about 3 times as long as broad, to 8 µm wide, with lateral walls sinuose. Cells of alar region to 8 µm wide, quadrate with rounded lumens, with lumen: wall ratio 3–4: 1; little different from more distal laminal cells. Costa filling 1/6 to 1/8 of immediate leaf base, little tapered above, short excurrent. Costa cross-section at leaf middle elliptic, about 3 times as thick as the adjacent leaf, with 6–10 cells exposed on adaxial surface and more than 15 cells exposed on abaxial surface. Leaf margin plane throughout. Awn not present on any leaf. Axillary hairs to 800 µm long, with more than ten rectangular, thin-walled cells, without a basal brown cell. Rhizoids dense and long in older portions of plant, red brown and monopodially branched, to 30 µm wide at base, smooth to finely verruculose. Stem cross-section round with a conspicuous central strand, with stereome yellow-brown, moderately differentiated from the somewhat pachydermous, hyaline inner cortical cells,

   Autoicous with perigonia located only a few leaf axils below perichaetia. Inner perichaetial leaves pale to hyaline, ovate-lanceolate, erect and markedly shorter than the capsule. Outer perichaetial leaves loosely sheathing capsule, mostly a little longer than the adjacent vegetative leaves, never with awn. Seta to 0.5 mm long, yellow to pale brown, straight and smooth. Urn immersed, erect, symmetrical and short-cylindric to elliptic, smooth when dry, to 1.2 mm long, about 1.5: 1, not strumose. Operculum rostrate, to half as long as urn. Annulus absent or indistinct. Calyptra mitrate to cucullate, lacerate basally, covering only operculum. Peristome vivid red-brown, to 500 µm long, finely striate-papillose, deeply and asymmetrically cribrose but without bifid forking. Suboral exothecial cells thin-walled in 1–3 rows, transversely elongate, to 15 µm wide, about 0.7: 1. Median exothecial cells very irregular in size and shape, 15–25 µm wide, not in regular vertical rows, quadrate to rectangular or hexagonal, 1–3: 1, thin-walled with lumen: wall ratio more than 5: 1. Basal exothecial cells smaller but otherwise undifferentiated. Stomata absent. Spores smooth to finely verruculose, to 9 µm.

Vouchers: Alpine Co.; Highway 4 about 4.8 miles west of Ebbetts Pass, Stanislaus National Forest, Shevock 19963 (determined by Blom); Lake Co.: Upper Nye Camp just north of Snow Mountain Wilderness boundary, Mendocino National Forest, Shevock, Bourell, & Toren 15839 (determined by Blom); Madera Co.: Minarets Road at Rock Creek, Sierra National Forest, Shevock & Kellman 19762 (determined by Blom): Riverside Co.: Seven Pines Trail, San Bernardino National Forest, Harpel 1131 (CAS); Tulare Co.: North Fork Kaweah River at junction with Redwood Creek, Kings Canyon National Park, Shevock 16642 (determined by Blom).

Literature: As Grimmia cinclidodontea Flowers 1973; Harpel 1980a; Harthill et al. 1979; Long 1978; Spjut 1971. As Grimmia pacifica Lawton 1979.

Illustration References: Malcolm et al. 2009 p. 76; Flowers 1973; Lawton 1971; Robinson and Hermann 1964.

Elevation by latitude plot for Schistidium cinclidodonteum
   in California