Crumia latifolia, Can. J. Bot. 44: 609. 1966. -- Merceya latifoia Kindb. in Mac., Bull. Torr. Bot. Club 16: 94. 1889. -- Scopelophila latifolia (Kindb.) Ren. & Card., Rev. Bryol. 19: 92. 1892.

   Plants in thick turfs or as scattered tufts to 2.5 cm high, dark-green mostly with a reddish-brown cast. Leaves in a comose apical cluster, spreading when moist but keeled along costa and loosely reflexed near margins when dry, obovate to spatulate, 3.5–4.5 mm long, about 2.5: 1. Median laminal cells pluripapillose with low and inconspicuous punctiform papillae, to 16 µm broad, in straight rows radiating from costa to leaf margin, with lumen/wall ratio 4–8: 1, quadrate to hexagonal with angular lumens and without corner thickenings. Basal juxtacostal cells rectangular with straight and thin lateral walls, to 30 µm broad, 2–5: 1, smooth. Marginal cells abruptly larger than median cells, about twice as deep as wide, mostly reddish pigmented, less papillose and thicker-walled than adjacent laminal cells. Basal marginal cells similar in size and shape to basal juxtacostal cells but more narrow. Costa red-brown, occupying about 1/6 of leaf base, tapering and percurrent to subpercurrent in the bluntly rounded to mucronate apex. Abaxial cells of costa narrowly rectangular, to 8 µm wide, 6–10: 1, smooth and thick walled. Adaxial cells of costa similar to the adjacent laminal cells. Costa cross-section nearly terete, with a strong dorsal stereid band, a single layer of guide cells, and with the dorsal and ventral epidermises well-demarcated. Margin entire throughout, mostly erect but with recurvature near base or at leaf middle. Axillary hairs to 250 µm, to 10 cells long, with one or two light brown basal cells. Rhizoids inserted on abaxial base of costa, pale brown, to 20 µm wide at base, smooth and sparingly branched. Stem round in cross-section, with out a central strand or with that strand very inconspicuous, with a poorly differentiated outer stereome of 1–2 layers and with those cells grading into the thinner walled and larger cells of the interior. Gemmae not seen.

   Dioicous. Perichaetial leaves little differentiated from vegetative leaves. Seta to 15 mm, red-brown, straight, smooth. Capsule erect or almost so, with the urn cylindric, to 3 mm, 3–5: 1. Operculum conic, 1/4–1/3 of urn length. Annulus differentiated in two rows of enlarged and thinner walled cells. Peristome teeth 16, cribrose to irregularly bifid, straight, pale to brownish, to 0.2 mm long, with almost no basal membrane, papillose-spiculose throughout. Stomata superficial, restricted to upraised pustules on the neck. Exothecial cells rectangular to short rectangular (2–4: 1) and thin-walled with lumen/wall ratio more than 4: 1, in somewhat rows, to 20 µm wide. Spores to 15 µm, nearly smooth.

   Crumia latifolia is unmistakeable in most of its expressions. Any large calcareous bryophyte with spatulate leaves with rounded obtuse apices and reddened margins should not be confused in the field for any other bryophyte. Scopelophila cataractae (Mitt.) Broth. is a moss seemingly restricted to areas of heavy metal ores, particularly copper. It has only one known locality in California -- rocks from copper mining activities near Copperopolis, xxxxx County. This difference in habitats may be the most reliable distinction between the two species: the so-called distinct papillae of Crumia are distinct only in relation to the indistinct papillae of Scopelophila.

Vouchers: Butte Co.: near Bidwell Bar, Feather River, Schofield 23138 (MO); Humboldt Co.: Tish-Tang Campground south of Hoopa, Norris 47305; Kern Co.: Cache Creek east of Horse Canyon, southern Piute Mountains, Shevock & Hare 14909; Los Angeles Co.: Twin Falls at La Cienega Camp North Fork San Gabriel Canyon north of Azusa, Angeles National Forest, F. & R. Drouet 3471 (UC); San Bernardino Co.: Caruthers Canyon, New York Mountains, Mojave National Preserve, Laeger & Davis 1334 (CAS); Santa Barbara Co.: canyon about 1 mile south of Bates Canyon Campground, Los Padres National Forest, Norris 55380; Santa Clara Co.: Stevens Canyon Road just east of Eden Canyon Road junction, Whittemore 5110 (MO); Trinity Co.: Highway 36 about 4 miles east of Wildwood, Shasta-Trinity National Forest, Norris 73561.

Literature: Bourell 1981; Christy and Wagner 1996; Harthill et al. 1979; Long 1978; Mishler 1978; Schofield 1966a; Shevock and Toren 2001; Toren 1977; Yurky 1990, 1995. As Merceya latifolia Koch 1950a; Koch and Ikenberry 1954; Moxley 1928; Thomson and Ketchledge 1958. As Scopelophila latifolia Flowers 1973; Lawton 1971.

Illustration References: Malcolm et al. 2009 p. 121; Flowers 1973; Lawton 1971; Schofield 1966a; Zander 1993.

Elevation by latitude plot for Crumia latifolia
   in California