Hygrohypnum smithii

   Plants to 30 mm long, in lustreless, olive-green to sordid-green mats, with stems rigid, green when young, turning almost black with age. Plants prostrate and irregularly branched with little differentiation of stems and branches. Branch axes prostrate to weakly decumbent, to 10 mm long. Leaves orbicular with bluntly rounded apices, to 1 mm long, not at all falcate, diverging from stem at about a 60 degree angle when wet or dry. Margins plane and entire but sometimes appearing minutely crenulate by collapse of the thin outer walls of those marginal cells. Median laminal cells of well-developed leaves elliptic rectangular, somewhat vermiculose, 3–8: 1, to 6 µm broad, smooth and moderately thick-walled with lumen: wall ratio 3–4: 1. Cells of alar region quadrate to short rectangular in a small group similar in width to that of adjacent more distal cells but markedly smaller than the adjacent more interior rectangular cells. Marginal cells not differentiated. Cells quadrate or nearly so in a large group across the blunt leaf apex. Costa single to near the leaf middle but usually forked distally. Pseudoparaphyllia elongate-lanceolate to filamentose, 3–5 cells long and 1–3 cells wide at base, to 80 µm long. Axillary hairs about 5-celled, of uniform diameter throughout, thin-walled, to 150 µm long, with no basal brown cell, not offset from leaf insertion. Stem cross-section with a stereome about 2 cells thick with thick-walled cells abruptly demarcated from an inner medulla of thin-walled and larger hyaline cells with central strand usually present but indistinct. Rhizoids scarse even on the older prostrate axes, fasciculate at abaxial leaf insertions, to 12 µm at insertion, red-brown, sparingly branched, smooth.

   Autoicous. Perichaetia placed on older prostrate stems with the outer bracts short and squarrose but with the inner bracts to 3 mm long, erect and closely sheathing the base of the seta. Inner perichaetial bracts costate and plicate, elliptic-lanceolate, mostly rather dark brownish green, gradually contracted from base to the bluntly rounded apex with no alar differentiation and with margins nearly entire. Seta to 12 mm long, smooth, erect, yellow-brown to brown. Urn pale-brown, to 1.5 mm long, about 1.5: 1, oblong-cylindrical, curved and inclined, not sulcate but lightly strangulate. Exothecial cells moderately thick-walled, not collenchymatous, not in regular rows, to 20 µm broad, mostly rounded isodiametric but irregular in size and shape, not strongly differentiated near the mouth. Stomata few, short and vertical pored, on lower portion of urn. Operculum apiculate, to 1/4 as long as urn. Annulus present, not revoluble. Calyptra cucullate and smooth, sheathing only distal half of capsule. Exostome teeth inserted and somewhat united near mouth of urn, to 400 µm long, lanceolate but with a prominent shoulder at about middle, transversely striate, inflexed when dry, pale yellow to yellow, with a well defined zig-zag median commisural line. Endostome segments papillose, nearly as long as exostome, consisting of keeled, narrow segments with 2 cilia, arising from a basal membrane about 1/2 as long as exostome. Spores to 18 µm, essentially smooth.

Vouchers: Fresno Co.: Forest Road 9S10 at tributary of Cow Creek, Sierra National Forest, Shevock 14207; Inyo Co.: Bighorn Sheep Zoological Area, Baxter Pass Trail, John Muir Wilderness, Inyo National Forest, Shevock & York 16545; Plumas Co.: stream near Quincy, Ikenberry 1322 (MO) [determined by Koch]; Shasta Co.: Drakesbad, Warner Valley, Lassen Volcanic National Park, Showers 2427 (UC); Siskiyou Co.: Sugar Lake west of Callahan, Klamath National Forest, Norris 57380 and Paynes Lake, Norris & Smith 46359.

Literature: Flowers 1973; Jamieson 1976; Koch 1950a, 1958; Koch and Ikenberry 1954; Lawton 1971; McGrew 1976; Showers 1982. As Hypnum arcticum Lesquereux 1868; Watson 1880.

Illustration References: Abramov and Volkova 1998; Flowers 1973; Jamieson 1976; Lawton 1971.

No illustrations found in database.

Elevation by latitude plot for Hygrohypnum smithii
   in California