Taxithelium planum (Brid.) Mitt.

Authority

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

Family

Sematophyllaceae

Scientific Name

Taxithelium planum (Brid.) Mitt.

Description

Species Description - Plants rather slender to medium-sized, in somewhat lustrous, ± soft, yellow-green, thin, often extensive, flat mats. Stems long-creeping, to ca. 15 cm long, but usually <10 cm, subpinnately branched, the branches prostrate to slightly ascending, complanate-to terete-foliate; in cross-section with 2-4 rows of small thick-walled green cells surrounding large thin- to firm-walled cells, central strand absent; pseudoparaphyllia foliose; axillary hairs with 1(-2) short brown basal cells and 2-3(-4) elongate hyaline distal cells. Stem and branch leaves ± similar, erect-spreading, crowded or rarely laxly foliate, complanate to terete, narrowly to broadly ovate, 0.63-1.2 X 0.3-0.6 mm, obtuse or acute to short-acuminate, concave; margins serrulate nearly to base, sometimes doubly so, plane; costa short and double or absent; cells linear, seriately pluripapillose with 5-9 papillae over each lumen at back, the papillae small and blunt, sometimes variously branched, thin-walled, becoming shorter and smooth in the apex, becoming shorter, smooth, thick-walled, and porose toward the insertion; alar cells 2-4, large, inflated, occasionally colored, with small marginal group of quadrate, thin-walled cells above them. Asexual propagula none. Autoicous. Perichaetial leaves elongate, erect, ± tortuous, lanceolate, 1-1.5 mm long, acuminate; margins serrulate to serrate, plane; costa very short and double or none; cells laxly hexagonal to linear, seriately pluripapillose or smooth; alar cells not differentiated. Setae elongate, slender, smooth, reddish, 0.8-2 cm long, usually curved at base of urn; capsules inclined, asymmetric, ovoid to short-cylindric, ca. 1 mm long, constricted below the mouth when dry and empty and at the base to a small neck; exothecial cells isodiametric to short-rectangular, somewhat collenchymatous, becoming smaller, oblate, and evenly thin-walled in 1-3 rows at the mouth; annulus not differentiated; operculum conic-rostrate; exostome teeth narrowly triangular, shouldered, bordered, on the front surface with a zig-zag median line, cross-striolate below, coarsely papillose above, trabeculate at back; endostome with a high basal membrane, segments yellow, finely papillose, broad, keeled, perforate, almost as long as the teeth, cilia single. Spores spherical, almost smooth or finely papillose, 10-15 pm diam. Calyptrae cucullate, naked, smooth.

Discussion

1. Taxithelium planum (Brid.) Mitt., J. Linn. Soc., Bot. 12: 469. 1869; Hypnum planum Brid., Muscol. Recent. Suppl. 2: 97. 1812, non Poir. in Steud., Nomencl. Bot. 2: 215. 1824, nom. nud. in syn. [= Trachyloma planifolium (Hedw.) Brid.], nec Schwãgr. in Gaudich. in Freyc., Voy. Uranie, Bot. 6: 228. 1828, hom, illeg.; Stereodon planus (Brid.) Mitt., J. Linn. Soc., Bot. 7: 157. 1863; Sigmatella plana (Brid.) Miill. Hal., Hedwigia 37: 259. 1898. Plate 141, figures 1-14; plate 142, figures 12-17 Leskea cymbifolia Brid., Bryol. Univ. 2: 333. 1827. Hypnum nepalense Schwügr., Sp. Musc. Frond. Suppl. 3(1): 226. 1828; Stereodon nepalensis (Schwãgr.) Mitt., J. Proc. Linn. Soc., Bot. Suppl. 1: 100. 1859; Trichosteleum nepalense (Schwãgr.) A. Jaeger, Ber. Thãtigk. St. Gallischen Naturwiss. Ges. 1876-77: 412. 1878; Taxithelium nepalense (Schwãgr.) Broth. in Warb., Monsunia 1:51. 1899. Hypnum planum var. flavescens Müll. Hal., Syn. Musc. Frond. 2: 265. 1851; Taxithelium planum var. flavescens (Müll. Hal.) Paris, Index Bryol. 1262. 1898. Taxithelium planum fo. subjulaceum Besch., Ann. Sci. Nat. Bot. VI, 3: 255. 1876, “subjulacea”; Taxithelium planum var. subjulaceum (Besch.) Besch. ex Paris, Index Bryol. Suppl. 317. 1900. Taxithelium planum var. distichum Besch., Ann. Sci. Nat. Bot. VI, 3: 256. 1876, “disticha." Sigmatella pseudoacuminatula Müll. Hal., Bull. Herb. Boissier 5: 214. 1897; Taxithelium pseudoacuminatulum (Miill. Hal.) Paris, Index Bryol. 1262. 1898. Taxithelium laxiusculum Renauld & Cardot, Rev. Bryol. 28: 110. 1901, nom. nud. Taxithelium planum var. hookerioides Bizot & Thér. in Thér., Mem. Soc. Cub. Hist. Nat. “Felipe Poey” 15: 223. 1941, nom. inval., Bizot & Thér. ex Bizot, Bull. Mens. Soc. Linn. Lyon 34: 326. 1965. Taxithelium planum fo. minutaefolia Thér., Mem Soc. Cub. Hist. Nat. “Felipe Poey” 15: 223. 1941, nom. inval. Discussion. Taxithelium planum is a common and widespread species colonizing most lowland habitats. It is usually easily recognized by the complánate, subpinnate, dirty-green plants with seriate papillae over the leaf lumina. The ovate leaves and quadrate alar cells subtended by a few enlarged, ± inflated cells will easily separate it from its congeners. The numerous varieties and forms described under this species seem to be nothing more than ecological growth forms. For example, the vars. distichum and acuminulatum (Hornsch.) Paris are forms growing in moist, shaded areas, whereas the var. flavescens grows in drier, more exposed localities. Additional, extralimital synonyms can be found in Buck (1985). A single specimen from the Cockpit Country of Jamaica (Britton 321, NY) is extremely unusual. Its long, acuminate leaves and more or less terete branches are anomalous in T. planum. However, unless it belongs to an undescribed or South American species, it fits better here than in any other Antillean taxon.

Distribution

Range. Florida, Mexico, Central America, northern and central South America, tropical Africa, Madagascar, India and southeastern Asia, northern Australia; Bahamas (New Providence), Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Puerto Rico (including Vieques), Virgin Islands (St. John, St. Thomas, Tortola), St. Martin, St. Eustatius, St. Kitts, Nevis, Antigua, Montserrat, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, Barbados, Grenada; growing on almost all substrates, but

United States of America North America| Mexico North America| Central America| South America| Africa| Madagascar Africa| India Asia| Asia| Australia Oceania| Bahamas South America| Cuba South America| Jamaica South America| Haiti South America| Dominican Republic South America| Puerto Rico South America| Virgin Islands South America| Saint Martin South America| Sint Eustatius South America| Saint Kitts and Nevis South America| Antigua and Barbuda South America| Montserrat South America| Guadeloupe South America| Dominica South America| Martinique South America| Saint Lucia South America| Saint Vincent and the Grenadines South America| Barbados South America| Grenada South America|