Pilosium chlorophyllum (Hornsch.) Müll.Hal.
-
Authority
Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
-
Family
Plagiotheciaceae
-
Scientific Name
-
Description
Species Description - Plants medium-sized, in lustrous, yellow-green, mostly dense, ± flat, often extensive mats. Stems creeping, to 6 cm long, irregularly branched, complanate-foliate; in cross-section with a unistratose hyalodermis, subtended by 1-3 rows of small firm-walled colored cells surrounding large thin-walled cells, central strand absent; pseudoparaphyllia filamentous; axillary hairs with a single short brown basal cell and 3-4 elongate hyaline or yellowish distal cells. Stem and branch leaves similar but lateral and dorsal leaves differentiated, crowded, ± stiff, somewhat curled when dry, curled downward when moist, complanate, dorsal leaves erect, oblong-ovate, 1.3-1.6 mm long, symmetric, lateral leaves wide-spreading, oblong-lanceolate, 1.5-2 mm long, cultriform, obtuse to short-acute, ± concave, not plicate, not decurrent; margins entire to serrulate above, entire below, plane; costa single in lateral leaves, very short to ca. 1/3 the leaf length, absent in dorsal leaves; cells linear, 89-146 X 7-12 µm, smooth, thin- to firm-walled, porose or not, heavily chlorophyllose, becoming conspicuously porose toward the insertion; alar cells strongly differentiated in lateral leaves, numerous, 24-89 X 14-28 µm, oblong, often colored, ± inflated, porose, extending across adaxial surface of costa, dorsal leaves with few differentiated cells, 12-24 X 9-12 µm, quadrate to subquadrate. Asexual propagula none. Autoicous. Perichaetia along stems, often in pairs; leaves broadly oblong-lanceolate, to ca. 2 mm long, acuminate, deeply incised to ca. 1/3 the leaf length; margins dentate to serrate in addition to incised, plane; costa none; cells linear, smooth, thick-walled, porose, shorter and broader across the colored insertion; alar cells not differentiated but stem hyalodermis sometimes stripping off and attached to leaf base. Setae elongate, smooth, orange-red, 1.5-1.8 cm long, straight; capsules cernuous, symmetric, not arcuate, short-cylindric, orange-red, 0.8-1.2 mm long, constricted below mouth when dry; exothecial cells quadrate to short-rectangular, ± thin-walled and collenchymatous, becoming smaller and with evenly thickened walls toward the mouth; annulus not differentiated; operculum short-rostrate, 0.4-0.6 mm long; exostome teeth narrowly triangular, shouldered, bordered, on the front surface cross-striolate in lower 2/3, papillose above, trabeculate at back; endostome with a high, finely roughened basal membrane, segments finely papillose, keeled, not or narrowly perforate, ca. as long as the teeth, cilia single, shorter than the segments. Spores spherical, finely papillose, 7-9 µm diam. Calyptrae cucullate, naked, smooth.
-
Discussion
1. Pilosium chlorophyllum (Hornsch.) Müll. Hal., Flora 83: 340. 1897; Hypnum chlorophyllum Hornsch. in Mart., Fl. Bras. 1(2): 89. 1840; Stereophyllum chlorophyllum (Hornsch.) Mitt., J. Linn. Soc., Bot. 12: 544. 1869. Plate 111, figures 1-7 Pilosium serrulatum R. S. Williams, J. Wash. Acad. Sci. 20: 178. 1930. Discussion. Pilosium chlorophyllosum is a very distinctive species. The complanate-foliate stems are usually in flat, extensive mats on rotting wood. The lateral and dorsal leaves are strongly differentiated with the lateral ones costate with numerous alar cells. In aspect it is most like a Plagiothecium, but the leaves are not at all decurrent as in that genus. The perichaetial leaves are very odd. Each is deeply incised on one or both sides of the apex, resulting in a leaf that appears bifid or trifid. Although the alar cells of the perichaetial leaves are not differentiated, sometimes patches of the hyalodermis strip off with dissection, making it appear as if there are decurrencies of quadrate cells.
-
Distribution
Range. United States (SW North Carolina), southernmost Mexico south through Central America, northern and central South America to Bolivia and central Brazil (Mato Grosso to Bahia), Trinidad; Hispaniola (Haiti and Dominican Republic); typically growing on rotten logs, less often on tree bases, litter or rocks, in humid forests, mostly below 400 m, but in Hispaniola to 2500 m.
United States of America North America| Mexico North America| Central America| Brazil South America| Bolivia South America| Peru South America| Ecuador South America| Colombia South America| Venezuela South America| Guyana South America| Suriname South America| French Guiana South America| Trinidad and Tobago South America| Haiti South America| Dominican Republic South America|