Hygroamblystegium fluviatile (Hedw.) Loeske

  • Authority

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

  • Family

    Amblystegiaceae

  • Scientific Name

    Hygroamblystegium fluviatile (Hedw.) Loeske

  • Description

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    Species Description - Plants medium-sized to large, in often lustrous, soft, mostly dark-green to blackish, rarely yellow-green, often extensive, dense mats. Stems creeping (except ascending when submerged), to ca. 8 cm long, usually much branched, the branches ascending to erect; in cross-section with 4-6 rows of small thick-walled cells surrounding larger thinner-walled cells, central strand none or rarely rudimentary; paraphyllia absent; pseudoparaphyllia foliose, small; axillary hairs with a single short brown basal cell and 1-2 elongate hyaline distal cells. Stem and branch leaves somewhat differentiated, stem leaves erect to erect-spreading, broadly oblong-lanceolate, 1.1-2.3 mm long, broadly acuminate; margins entire or subserrulate in the acumen, plane; costa broad, dark, disappearing in the acumen; cells rhomboidal to short-hexagonal, ca. 3-6:1, smooth, firm-walled, becoming broader toward the yellowed insertion; alar cells scarcely differentiated. Branch leaves erect to erect-spreading, oblong-lanceolate, 0.6-1.6 mm long, broadly and bluntly acuminate, otherwise as in stem leaves. Asexual propagula none. Autoicous. [Sporophytes not seen; description from Cheney (1897: 275-277).] Perichaetial leaves ovate to ovate-lanceolate, acute to short-acuminate; margins entire or denticulate at apex; costa extending into erect apex; cells linear. Setae elongate, smooth, stout, purple below, light-brown to yellow above, 1.5-3.5 cm long; capsules inclined to horizontal, arcuate, asymmetric, subcylindric, 1.5-3.5 mm long, ± constricted below the mouth when dry; exothecial cells short-rectangular, stomata numerous, scattered; annulus broad, of 2-3 rows of cells; operculum conic, acute to apiculate; exostome teeth on the front surface cross-striolate below, papillose above, trabeculate at back; endostome papillose, with a high basal membrane, segments keeled, narrowly perforate, shorter than the teeth, cilia in groups of 2-3, nodulose to subappendiculate. Spores spherical, finely papillose, 16-26 µm [12-18 µm fide Smith (1978: 555)] diam.

  • Discussion

    2. Hygroamblystegium fluviatile (Hedw.) Loeske, Moosfl. Harz. 299. 1903; Hypnum fluviatile Hedw., Sp. Musc. Frond. 277. 1801; Amblystegium fluviatile (Hedw.) Schimp. in Bruch, Schimp. & W. Gümbel, Bryol. Eur. 6(fasc. 55-56, Monogr. 1): 55. 1853; Hypnum irriguum Hook. & Wilson subsp. fluviatile (Hedw.) Boulay, Musc. France 1: 73. 1884, comb, inval. Plate 82, figures 7-12 Discussion. Hygroamblystegium fluviatile is characterized by oblong-lanceolate leaves and a broad, nonflexuose costa disappearing in the broad, blunt leaf apex. The species typically grows beside or in small, cold streams. It may be separated from H. varium by the wetter habitat, more robust plants, stronger costae, and longer median leaf cells.

  • Distribution

    Range. Eastern North America, Guatemala, Peru, Europe; Hispaniola (Dominican Republic); in the West Indies the species is relatively common in the Dominican Republic, on rocks and bases of trees beside small, cold streams, above 2100 m.

    North America| Guatemala Central America| Peru South America| Europe| Dominican Republic South America| West Indies|