Nat. Pfl. 1(3): 1040. 1908. -- Hypnum molle (Hedw.) Loeske ssp. bestii Ren. & Bryhn, Bull. Ac. Int. Geogr. Bot. 10: 7. 1901. -- Hygrohypnum molle (Hedw.) Loeske ssp. bestii (Ren. & Bryhn) Grout, Check List Pleur. Moss. N. Amer. 16. 1929.
Plants to 100 mm long, in lustreless, olive-green to sordid-green mats usually with a russet wash in exposed areas. 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 20 mm long. Leaves broadly ovate to almost orbicular with bluntly rounded apices, to 3 mm long, not at all falcate, diverging from stem at more than a 45 degree angle when wet or dry. Margins plane and entire but usually with light serrulations at the blunt apex. Median laminal cells of well-developed leaves linear-vermiculose, 6–10: 1, to 6 µm broad, smooth or with weak cuticular striations, thick-walled with lumen: wall ratio 2–3: 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, especially in proximal half of leaf, broader and 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 mostly forked from near the base, with both forks extending to near the leaf middle. Pseudoparaphyllia broadly ovate and rounded at apex, closely folded over bud, to 400 µm long. Axillary hairs 6–8-celled, of uniform diameter throughout, thin-walled, to 400 µm long, with two of the basal cells short but concolorous, not offset from leaf insertion. Stem cross-section with a stereome 2–4 cells thick with those thick-walled cells abruptly demarcated from an inner medulla of thin-walled and larger hyaline cells with central strand usually present but indistinct. Rhizoids scarce even on the older prostrate axes, fasciculate at abaxial leaf insertions, to 12 µm at insertion, red-brown, sparingly branched, smooth.
Dioicous. 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 ecostate to weakly costate, plicate, narrowly 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 20 mm long, smooth, erect, red-brown. Urn pale-brown, to 2 mm long, about 2: 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 20 µm, finely papillose.
|Literature||Flowers 1973; Ireland 1982; Jamieson 1969, 1976; Kellman 2003; Koch 1950a; Lawton 1966, 1971; McGrew 1976; Showers 1982; Yurky 1990, 1995. As Hypnum bestii Williams 1901. As Limnobium bestii Holzinger 1901.|
|Illustrations||Malcolm et al. 2009 p. 235; Czernyadjeva 2000; Flowers 1973; Ireland 1982; Jamieson 1976; Lawton 1966, 1971.|
|Bioregions||CaR, CW, MP, NW, SN, SNE.|
|Vouchers||Del Norte Co.: Knopti Creek road about 9 miles east of Highway 199, Norris 7754 (determined by Jamieson); Inyo Co.: Taboose Creek Trail, John Muir Wilderness, Inyo National Forest, Shevock 13880; Lake Co.: Big Spring, Boggs Mountain State Forest, Toren & Dearing 7108 (CAS); Modoc Co.: Soup Creek Campground east of Likely, Modoc National Forest, Norris 9450 (determined by Jamieson); Plumas Co.: Domingo Springs about 8 air miles northwest of Chester, Lassen National Forest, Shevock & Corbin 12233; Riverside Co.: Devils Slide Trail, San Jacinto Wilderness, San Bernardino National Forest, Shevock, Kramer, Hall, & Ward 24061; Santa Cruz Co.: Castle Rock Falls, Castle Rock State Park, Kellman 2259 (CAS); Siskiyou Co.: trail between Abbott Ranch and English Lake, Marble Mountain Wilderness, Klamath National Forest, Spjut 1358 (UC) [determined by Jamieson].|