Leucomium

  • Authority

    Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.

  • Family

    Leucomiaceae

  • Scientific Name

    Leucomium

  • Description

    Species Description - Plants procumbent, forming dense or thin, glossy or dull, typically pale- to whitish-green (occasionally bright green or yellow-green) mats. Primary stems creeping, secondary stems horizontal to shortly ascending, pale yellowish-green, fragile, sparsely or densely, irregularly branched, the branches identical to the stems; epidermal cells quadrate to short-rectangular; in cross-section stem cells homogeneous, thin-walled throughout, central strand absent; rhizoids reddish-brown, smooth, restricted to the substrate side of the stems and in abaxial groups at the base of the leaves; pseudoparaphyllia absent; paraphyllia absent. Leaves variously dimorphic, densely foliate, typically complanate, the leaf margins plane whether wet or dry, or more or less falcate, the margins erect to incurved when dry; lateral leaves spreading, dorsal leaves erect (at times distinctly broader and more shortly, abruptly pointed than the lateral leaves, ventral leaves flattened, erect; leaves lanceolate-acuminate, oblong-triangular or ovate-lanceolate to oblong-ovate, gradually or abruptly short- to long-acuminate, symmetric or asymmetric; margins absolutely entire, unbordered; absolutely ecostate; cells smooth, long-hexagonal, rhomboidal or linear, lax- or firm-walled; alar cells not differentiated. Axillary hairs two-celled: basal cell square, red-brown, terminal cell long-rectangular, rounded at the apex, hyaline. Synoicous, autoicous or polyoicous. Setae elongate, red to red-brown, smooth throughout or more or less warty below the base ofthe capsules; capsules red to red-brown, pendulous to erect-curved and cylindric to ovoid, commonly constricted below the mouth when dry, smooth throughout or warty at base, phaneropore stomata present in neck region; exothecial cells short-rectangular, collenchymatous; opercula longrostrate; peristome diplolepideous and double, exostome teeth 16, dark red, inflexed when wet, reflexed when dry, dorsal surface commonly with a zig-zag median line (occasionally absent), dorsal lamellae densely striate below, the striae usually not reaching the median line, the teeth therefore variably furrowed (occasionally furrow absent), coarsely papillose above, dorsal trabeculae moderately projecting, ventral lamellae smooth, ventral trabeculae weakly projecting below, strongly projecting above; endostome pale yellow to white, smooth to weakly papillose, equal in size to the exostome teeth, membrane high, the vertical walls on the ventral surface strongly thickened and projecting, segments keeled, more or less perforate, cilia absent or rudimentary. Spores spherical, finely papillose. Calyptrae cucullate, smooth and pale yellowish below, reddish at times roughened above, naked or with a few long, uniseriate, hyaline and fragile hairs.

  • Discussion

    Leucomion Mitt, ex Mitt, in Seemann, Fl. Vit. 444. 1873, orthogr. var.; Leucomnium Mitt, ex C. Müll. in Reinecke, BoL Jahrb. Syst. 23: 330. 1896, orthogr. var. Type: L. debile (Sull.) Mitt. Hookeria debilis Sull., Proc. Amer. Acad. Arts 3: 79. 1855.

    Etymology. Apparently a combination of the Latin leuc(o)-: [Gk. leuk(o)-] white and the Greek -mium: (orthographic variant of mnium) moss; a reference to "the soft, pale, almost white foliage of the species" (Mitten, 1869).

  • Distribution

    Distribution. CENTRAL AMERICA: Mexico, Guatemala, Belize, El Salvador, Nicaragua, Costa Rica (including Cocos Island) and Panama. CARIBBEAN: Cuba, Jamaica, Hairi, Dominican Republic, Puerto Rico, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, Grenada, Tobago and Trinidad. SOUTH AMERICA: Colombia, Venezuela, Guyana, Surinam, French Guiana, Ecuador, Peru, Brazil and Bolivia. AFRICA: Guinea, Liberia, Ivory Coast, Ghana, Nigeria, Cameroon, Equatorial Guinea (Fernando Po), Gabon, Angola, C

    Mexico North America| Guatemala Central America| Belize Central America| El Salvador Central America| Nicaragua Central America| Costa Rica South America| Panama Central America| Cuba South America| Jamaica South America| Haiti South America| Dominican Republic South America| Puerto Rico South America| Guadeloupe South America| Dominica South America| Martinique South America| Saint Lucia South America| Saint Vincent and the Grenadines South America| Trinidad and Tobago South America| Colombia South America| Venezuela South America| Guyana South America| Suriname South America| French Guiana South America| Ecuador South America| Peru South America| Brazil South America| Bolivia South America| Guinea Africa| Liberia Africa| Ivory Coast Africa| Ghana Africa| Nigeria Africa| Cameroon Africa| Equatorial Guinea Africa| Gabon Africa| Angola Africa| Congo Africa| Central African Republic Africa| Zaire Africa| Uganda Africa| Tanzania Africa| Madagascar Africa| Seychelles Africa| Sri Lanka India Asia| Thailand Asia| Malaysia Asia| Indonesia Asia| Philippines Asia| Papua New Guinea Asia| New Caledonia Fiji Samoa Oceania|