Pilotrichum evanescens (Müll.Hal.) Crosby

  • Authority

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

  • Family

    Pilotrichaceae

  • Scientific Name

    Pilotrichum evanescens (Müll.Hal.) Crosby

  • Description

    Species Description - Plants small to moderately robust, in dull, yellow-green to golden-brown, often extensive patches. Stems creeping, with the leaves usually eroded, the primary branches erect, 2-8 cm tall, usually ca. 3-4 cm tall, irregularly and laxly pinnate to densely and regularly pinnate to bipinnate; in cross-section with 6-9 rows of small thick-walled small-lumened colored cells surrounding larger thin- to firm-walled cells, central strand none; pseudoparaphyllia filamentous to narrowly foliose; axillary hairs 2-celled, with a short brown basal cell and an elongate hyaline distal cell. Secondary branch leaves fairly crowded, erect when dry, spreading when moist, ovate to oblong-ovate, 0.9-1.3(-l.6) mm long, gradually acute to abruptly short-acute, strongly concave, decurrent; margins serrulate throughout, plane or sometimes incurved above, often narrowly recurved below; costa double, ± unequal, ± divergent throughout, ending 1/2-4/5 the leaf length, not crested or with a low crest 1 cell high; cells oval to rounded-oblong, often strongly prorulose, thick-walled, ± porose, apical cells scarcely differentiated, becoming more conspicuously porose toward the insertion and into the decurrencies; alar cells not differentiated. Asexual propagula frequently produced at base of costa, uniseriate, hyaline, to ca. 20 cells long, lightly roughened. Dioicous. Perichaetia inconspicuous, on primary and secondary branches; leaves erect, lanceolate, 1.2-2 mm long, gradually acuminate, concave, short-decurrent; margins serrulate above, subentire below, plane or irregularly and narrowly incurved; costa absent or short and double; cells ± linear, subflexuose, prorulose, thick-walled, ± porose, often somewhat shorter in the acumen, more strongly porose toward the insertion. Setae short, stout, roughened, reddish, 0.6-1.3 mm long, straight; capsules exserted, erect, cylindric, symmetric, ca. 2 mm long; exothecial cells subquadrate to short-rectangular, thin- to firm-walled, not collenchymatous; annulus of a single row of thick-walled, rectangular cells; operculum stoutly short-rostrate from a high-conic base; exostome teeth pale, narrowly triangular, not bordered, not shouldered, on the front surface with a straight or obscurely zig-zag median line, spiculose throughout, scarcely or not trabeculate at back; endostome pale, spiculose, with a low basal membrane, segments slender, not keeled, not perforate, shorter than the teeth, cilia none. Spores mostly spherical, finely papillose, 12-17 µm diam. Calyptrae mitrate, lobed at base, hairy, the hairs ± straight, 1-2-seriate, roughened above.

  • Discussion

    7. Pilotrichum evanescens (Müll. Hal.) Crosby, Bryologist 72: 326. 1969; Callicosta evanescens Miill. Hal., Linnaea 21: 189. 1848; Pilotrichum bipinnatum var. evanescens (Müll. Hal.) Müll. Hal., Syn. Musc. Frond. 2: 179. 1851. Plate 29, figure 7; plate 32, figures 5-10 Pilotrichum dubium Mitt., J. Linn. Soc., Bot. 12: 390. 1869. Pilotrichum cryphaeoides Besch., Ann. Sci. Nat. Bot. VI, 3: 219. 1876. Discussion. Pilotrichum evanescens is uniquely characterized, among the Antillean species of the genus, by the costa that diverges throughout its length and ends about 1/2-3/4 the leaf length. The leaves are often very concave and the laminal cells conspicuously prorulose.

  • Distribution

    Range. Mexico to Panama, Brazil, Guyana, Surinam, French Guiana, Trinidad and Tobago; Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Puerto Rico, St. Kitts, Nevis, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent, Grenada; growing on trees and shrubs, occasionally logs, in moist forests, at sea level to 500 m, occasionally higher.

    Mexico North America| Central America| Brazil South America| Guyana South America| Suriname South America| French Guiana South America| Trinidad and Tobago South America| Cuba South America| Jamaica South America| Haiti South America| Dominican Republic South America| Puerto Rico South America| Saint Kitts and Nevis South America| Guadeloupe South America| Dominica South America| Martinique South America| Saint Lucia South America| Saint Vincent and the Grenadines South America| Grenada South America|