Hygrohypnum styriacum

   Plants to 30 mm long, in lustreless to rather glossy, light green to olive-green mats, with stems mostly green. Plants prostrate and irregularly branched with little differentiation of stems and branches. Branch axes prostrate to weakly decumbent, to 10 mm long. Leaves to 1.5 mm long, about 2: 1, ovate-lanceolate and falcate-secund, closely crowded at stem apex but approximate below. Margins plane to ascending throughout, entire. Median laminal cells of well-developed leaves elliptic rectangular, somewhat vermiculose, 3–8: 1, to 7 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 adjacent more interior cells. Marginal cells not differentiated. Cells of leaf apex short elliptical, mostly 1–2: 1. Costa forked from a few cells above the base with both forks reaching nearly to midleaf. Pseudoparaphyllia elongate-lanceolate, 3–5 cells long and 2–3 cells wide at base, to 100 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 2–3 cells thick with very thick-walled cells abruptly demarcated from an inner medulla of thin-walled and larger hyaline cells without a central strand. Rhizoids primarily restricted to the older prostrate axes, fasciculate at abaxial leaf insertions, to 12 µm at insertion, red-brown, sparingly branched, smooth.

   Autoicous. Perichaetia clustered with perigonia on older and prostrate stems with the bracts to 3 mm long, erect and loosely sheathing the base of the seta. Perichaetial bracts lightly plicate, regularly lanceolate, pale to bleached light green, gradually contracted from base to the acute apex with no alar differentiation and with margins nearly entire. Seta to 20 mm long, smooth, erect, yellow-brown to brown. Urn pale-brown, to 2 mm long, about 2: 1, oblong-cylindrical and inclined, not sulcate but lightly strangulate. Exothecial cells thin-walled, not collenchymatous, not in regular rows, to 30 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 250 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 commissural line. Endostome segments smooth or nearly so, 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.: Mist Falls Trail near junction of Bubbs Creek, Kings Canyon National Park, Shevock & York 14469; Inyo Co.: east of Dragon Peak and north of Golden Trout Lake near Onion Valley, John Muir Wilderness, Inyo National Forest, Norris 46717; Mono Co.: Highway 120 below Ellery Lake east of Tioga Pass, Inyo National Forest, Shevock 13784 (determined by Jamieson) and Koenig Lake near Leavitt Lake east of Sonora Pass, Toiyabe National Forest, Norris 57177.; Trinity Co.: Bullards Basin, Shasta-Trinity National Forest, Norris 9287.

Literature: Jamieson 1976.

Illustration References: Malcolm et al. 2009 p. 237; Jamieson 1976.

Elevation by latitude plot for Hygrohypnum styriacum
   in California