Hygrohypnum molle

   Plants to 30 mm long, in lustreless, olive-green to yellow-green wefts. Stems flaccid, green when young, turning brown with age. Plants initially prostrate but becoming almost erect or pendent in water because of crowding, sparingly branched with little differentiation of stems and branches. Leaves rather distantly inserted on stem, ovate to ovate lanceolate with bluntly rounded apices, to 1.8 mm long, about 2: 1, somewhat to not at all falcate, weakly ascending when dry, erect-spreading when moist. Margins plane and entire below, usually with slight basal recurvature into the 2–4 cell long decurrency. Median laminal cells of well-developed leaves elliptic rectangular, 6–8: 1, to 6 µm broad, smooth, thick-walled and pitted with lumen: wall ratio about 1: 1. Cells of alar region shorter and more rectangular than median cells but otherwise not differentiated. Marginal cells, especially in distal half of leaf, markedly more pellucid than adjacent interior cells. Cells in a large group at leaf apex short rectangular 2–4: 1, thick-walled with lumen: wall ratio mostly less than 1: 1. Costa rather slender, of about ten cells wide at base, forked from near the base, with both forks ending near the leaf middle or below. Pseudoparaphyllia nearly fliamentose, of 3–4 cells in length and only 2 cells in width, to 60 µm long. Axillary hairs 5-celled, of uniform diameter throughout, thin-walled, to 250 µm long, with two of the basal cells short but concolorous, not offset from leaf insertion. Stem cross-section with a stereome 2–3 cells thick with those thick-walled cells abruptly demarcated from an inner medulla of thin-walled and larger hyaline cells with central strand usually obvious. 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 2 mm long, erect and closely sheathing the base of the seta. Inner perichaetial bracts weakly costate to about leaf middle, plicate, narrowly elliptic lanceolate, mostly rather dark brownish green, gradually contracted from base to the acute apex with no alar differentiation and with margins nearly entire. Seta to 10 mm long, smooth, erect, pale- to red-brown. Urn pale-brown, to 1.5 mm long, about 2: 1, oblong-cylindrical, curved and inclined, not sulcate but lightly strangulate. Exothecial cells rather thin-walled, not collenchymatous, not in regular rows, to 25 µm broad, mostly rounded hexagonal, not strongly differentiated near the mouth. Stomata few, short and vertical pored, on lower portion of urn. Operculum conic to inconspicuously apiculate, to 1/5 as long as urn. Annulus present, not revoluble. Calyptra cucullate and smooth, sheathing only distal half of capsule. Exostome teeth inserted somewhat below mouth of urn, to 250 µm long, lanceolate but with a prominent shoulder at about middle, transversely striate, inflexed when dry, yellow to orange 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 16 µm, finely papillose.

Vouchers: El Dorado Co.: Round Lake, Eldorado National Forest, Norris 71162; Fresno Co.: Taboose Pass Trail, headwaters of the South Fork Kings River, Kings Canyon National Park, Shevock 13867; Placer Co.: canyon feeding Ward Creek near junction with Courchevel Road, Whittemore 3075 (MO); Plumas Co.: stream near Johnsville, Ikenberry 371 (MO); Riverside Co.: North Fork San Jacinto River, San Jacinto State Park, Harpel 1122 (pers. herb.) [confirmed by Schofield]; Tulare Co.: Kern Plateau, Sirretta Creek above Big Meadow, Sequoia National Forest, Shevock 17511 and trail between Silliman Pass and Lodgepole, Sequoia National Park, Norris 46516; Tuolumne Co.: Deadman Creek off of Highway 108 wet of Sonora Pass, Stanislaus National Forest, Shevock 18599 (determined by Ochyra).

Literature: Flowers 1973; Frantz and Cordone 1967; Harpel 1980a; Harthill et al. 1979; Jamieson 1976; Koch 1950a, 1958; McGrew 1976; Showers 1982; Spjut 1971; Strid 1974; Toren 1977.

Illustration References: Flowers 1973; Jamieson 1976; Lawton 1971.

No illustrations found in database.

Elevation by latitude plot for Hygrohypnum molle
   in California