Cyrto-hypnum

• Authority

  Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.

• Family

  Thuidiaceae

• Scientific Name

  Cyrto-hypnum

• Description

  
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  Genus Description - Plants small and slender, in typically stiff, mostly green but occasionally golden, lax mats. Stems creeping, 1-2-pinnate, not fron-dose; in cross-section with small thick-walled cells surrounding larger thinner-walled cells, central strand small; paraphyllia few to relatively abundant, usually confined to stems, filamentous, mostly unbranched, just the distal cell or all cells papillose, the distal cell rarely pointed; pseudoparaphyllia foliose; axillary hairs usually with a single short brown basal cell and a single elongate hyaline distal cell. Stem and branch leaves typically strongly differentiated, stem leaves mostly broadly ovate, acuminate, seldom plicate, mostly short-decurrent or subauriculate; margins mostly crenulate-papillose, less often serrate to serrulate, often recurved at least below; costa single, usually strong but not filling the acumen; cells quadrate to short-rectangular, mostly pluripapillose, occasionally unipapillose, always on both surfaces, the papillae (when pluripapillose) usually arranged around the periphery of the lumina, thin- to firm-walled, sometimes becoming more elongate in the acumen; alar cells not differentiated. Branch leaves mostly smaller than stem leaves, rarely ca. the same size, lanceolate to oblong to ovate, obtuse to rarely short-acuminate, usually concave, not plicate, not or slightly decurrent; margins mostly crenulate-papillose, less often serrate to serrulate, usually plane; costa single, weaker than in stem leaves, sometimes projecting as a spine at apex; cells mostly isodiametric, mostly pluripapillose, occasionally unipapillose, always on both surfaces, the papillae (when pluripapillose) usually arranged around the periphery of the lumina, thin- to firm-walled; alar cells not differentiated. Asexual propagula none. Autoicous. Perichaetia conspicuous; leaves greatly enlarged, mostly erect, mostly lanceolate, acuminate; margins serrulate, ciliate or not, plane; costa single; cells more elongate than in vegetative leaves, often smooth. Setae elongate, slender, smooth or roughened either throughout or just above, reddish; capsules suberect to horizontal, rarely ± pendent, often asymmetric and arcuate, cylindric; exothecial cells quadrate to short-rectangular, thin- to firm-walled, not collenchymatous; annulus differentiated; operculum conic, often obliquely rostrate; exostome teeth yellow to yellow-brown, shouldered, bordered, on the front surface cross-striolate below, sometimes with overlying papillae, papillose above, trabeculate at back; endostome mostly with a high basal membrane, segments keeled, perforate or not, cilia in groups of 1-2, rarely rudimentary. Spores spherical, usually finely papillose. Calyptrae cucullate, mostly naked, smooth or roughened above.

• Discussion

  Cyrto-hypnum (Hampe) Hampe & Lorentz in Hampe, Bot. Zeitung (Berlin) 27: 455. 1869; Hypnum sect. Cyrtohypnum Hampe, Ann. Sci. Nat. Bot. V, 5: 310. 1866, nom. nud.; Hypnum subgen. Cyrto-hypnum Hampe, Flora 50: 78. 1867. Thuidium sect. Minutula Bruch & Schimp. in Bruch, Schimp. & W. Gümbel, Bryol. Eur. 5(fasc. 49/51, Monogr. 1): 161. 1852. Thuidium subgen. Microthuidium Limpr. in Rabenh., Rabenh. Krypt.-Fl., ed. 2, 4(2 [Laubm. Deutschl.]): 822. 1895; Thuidium sect. Microthuidium (Limpr.) Kindb., Eur. N. Amer. Bryin. 1: 54. 1896 [1897], nom. illeg.; Microthuidium (Limpr.) Warnst., Krypt.-Fl. Brandenburg 2: 677. 1905. Thuidium subgen. Thuidiella Schimp. ex Besch., Mém. Soc. Sci. Nat. Cherbourg 16: 235. 1872, nom. nud., Schimp. ex Broth, in Engl. & Prantl, Nat. Pflanzenfam. 1(3): 1012. 1908, nom. illeg. Discussion. In Cyrto-hypnum the small, autoicous plants have leaf cells typically pluripapillose, but more importantly the papillae occur on both leaf surfaces, rather than just at back, as in Thuidium. The paraphyllia are simple or rarely little-branched. The axillary hairs are 2- rather than 3-celled. The setae are commonly, but far from always, roughened. Probably the easiest way to recognize Cyrto-hypnum is by the small size of the plants. Since they are mostly fertile, it is usually not difficult to verify the sexuality. In the pluripapillose species (the vast majority), the papillae are arranged around the periphery of the lumina rather than over them (as in, e.g., Thuidium tomentosum). The 2-celled axillary hairs are tedious to observe because the leaves at the apices of branches are so small it is difficult to dissect them individually from the branch. Plants of Cyrto-hypnum often occur in calcareous habitats. They are always small, and often grow intermixed with other mosses, thus making them easy to overlook.