Thamnobryum fasciculatum (Sw. ex Hedw.) I.Sastre
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Authority
Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
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Family
Neckeraceae
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Scientific Name
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Description
Species Description - Plants robust, stipitate-frondose, in slightly lustrous, dark- to yellow-green, often dense colonies. Primary stems creeping, secondary stems arising from upturning primary stem, the creeping stem continuing by innovations near the base of the stipe, the secondary stems distinctly stipitate, 5-15(-20) cm tall, erect to pendent, pinnately to irregularly branched, ± complanate-foliate; in cross-section with 5-6 rows of small thick-walled cells surrounding larger thinner-walled cells, central strand small, of small thin-walled cells; paraphyllia absent; pseudoparaphyllia foliose; axillary hairs with 1-2(-5) short brown basal cells and 2-5 elongate hyaline to yellowish distal cells. Primary creeping stem leaves widely spaced, appressed with wide-spreading to squarrose apices, not complanate, broadly triangular, to ca. 1.3 mm long, narrowly acuminate, ± channelled above, narrowly decurrent; margins subentire throughout except for a few small teeth at extreme base, sometimes serrulate at base of acumen; costa diffuse, ± single and very short or short and double to absent; cells rounded linear-rectangular, ca. 10-15:1, smooth, thick-walled, porose, becoming shorter across the insertion; alar cells little differentiated, usually with a few subquadrate to short-rectangular cells along the basal margins, corresponding to the marginal teeth. Stipe leaves appressed with erect-spreading apices, not complanate, ovate-triangular, 2.1-2.5(-3) mm long, short- to long-acuminate, ± channelled above, decurrent; margins subentire above, serrulate below; costa single, ending 1/3-2/3 the leaf length; cells linear, 12-20:1, smooth or prorulose, firm-walled, porose, becoming shorter toward the insertion; alar cells not or scarcely differentiated. Secondary stem (continuation of stipe above branching) and branch leaves similar, ± complanate, erect-spreading, ovate-ligulate, 2.2-3.5(-4) mm long, obtuse and apiculate to acute, typically plicate, especially when dry, not decurrent; margins serrate above, the teeth unicellular, serrulate to base, plane or narrowly recurved near midleaf; costa single, strong, ending ca. 9/10 the leaf length, not projecting at apex; cells long-hexagonal at midleaf, ca. 6-8:1, smooth to prorulose, thin- to firm-walled, not or slightly porose, in upper ca. 1/5 of leaf the cells becoming conspicuously shorter, ca. 1-2:1, mostly ± hexagonal but sporadically subquadrate to rhombic, becoming long-rectangular and porose toward the insertion; alar cells not or scarcely differentiated. Asexual propagula not seen. Dioicous. Perichaetial leaves oblong-ovate, 1.6-2 mm long, abruptly acuminate; margins subentire, plane; costa single to ca. midleaf or absent; cells ± linear-rectangular above, ca. 8-12:1, smooth, thick-walled, porose, becoming shorter and broader toward the insertion. [Sporophytes not known from the West Indies; description based on South American material.] Setae elongate, smooth, red-brown, 1.5-2.5 cm long; capsules horizontal to pendent, cylindric, 1.6-2.8 mm long; exothecial cells short-rectangular, firm- to thick-walled, not becoming smaller toward the mouth; annulus of 2 rows of small thick-walled cells; operculum obliquely rostrate from a conic base, ca. 1.4 mm long; exostome teeth on the front surface cross-striolate below, papillose above, strongly trabeculate at back; endostome with a high, smooth to sparsely papillose basal membrane, segments papillose, keeled, perforate to gaping, ca. as long as the teeth, cilia in groups of 3, appendicu -late. Spores spherical, ± smooth, 10-14 µm diam. Calyptrae not seen.
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Discussion
1. Thamnobryum fasciculatum (Hedw.) I. Sastre in I. Sastre & W. R. Buck, Caribbean J. Sci. 29: 232. 1993; Hypnum fasciculatum Hedw., Sp. Muse. Frond. 245. 1801; Neckera fasciculata (Hedw.) Arn., Mém. Soc. Linn. Paris 5: 292. 1826; Porotrichum fasciculatum (Hedw.) Mitt., J. Linn. Soc., Bot. 12: 468. 1869; Thamnium fasciculatum (Hedw.) Müll. Hal., Hedwigia 37: 260. 1898; Porothamnium fasciculatum (Hedw.) M. Fleisch., Musci Buitenzorg 3: 927. 1908. Discussion. Thamnobryum fasciculatum is a robust moss typically growing on moist rocks by streams and waterfalls. When growing on vertical rocks the fronds point downward, but when growing on horizontal rocks the fronds are ± flat-topped. The stipe leaves are broadly triangular with ± linear cells. The leaves of branches and secondary stems are similar and ovate-ligulate with a broad apex, a strong single costa, and short, hexagonal apical cells. The plants are differentiated from T. tumidicaule by a more robust stature, plicate leaves, and hexagonal rather than rhomboidal apical leaf cells. From Homaliodendron flabellatum, which is of comparable size, T. fasciculatum may be distinguished by the leaves with unicellular teeth and by stems with a central strand. From Porotrichum the genus differs by short-decurrent leaves with a stronger costa and short apical cells.
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Distribution
Range. Panama, Venezuela, Colombia to Bolivia, eastern Brazil, Trinidad; southeastern Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Puerto Rico; growing in very moist and shaded habitats, especially rocks and soil near waterfalls and streams, at 800-1800(-2200) m.
Panama Central America| Venezuela South America| Colombia South America| Ecuador South America| Peru South America| Bolivia South America| Brazil South America| Trinidad and Tobago South America| Cuba South America| Jamaica South America| Haiti South America| Dominican Republic South America| Puerto Rico South America|