Pilotrichella flexilis (Hedw.) Ångstr.
-
Authority
Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
-
Family
Lembophyllaceae
-
Scientific Name
-
Description
Species Description - Plants typically robust, in ± lustrous, ± stiff, green to golden to brownish, mostly dense colonies. Stems creeping or more often pendent, to ca. 40 cm long, but usually ca. 15-20 cm, freely branched, the branches turgid, mostly simple, to ca. 3 cm long, obtuse at apices or apical 1(-3) mm often cuspidate because of appressed leaves; in cross-section with 5-7 rows of small thick-walled cells surrounding larger ± firm-walled cells, central strand none; paraphyllia absent; pseudoparaphyllia broadly foliose; axillary hairs with (l-)2 short brown basal cells and 2(-4) elongate hyaline (or rarely brown) distal cells. Stem and branch leaves scarcely differentiated but those of the stem often eroding with time, not or scarcely seriately ranked, spreading to wide-spreading, broadly oblong-ovate, (1.4-)1.7-2(-2.3) mm long, often cuspidate, typically shortly and broadly mucronate, rarely to 0.15 mm long but typically ca. 0.06 mm long and often recurved, concave, subauriculate; margins mostly subentire throughout but sometimes serrulate above, directly below the muero, broadly incurved above; costa short and double or absent; cells long-hexagonal to linear, smooth, thick-walled, strongly porose, becoming shorter and broader above alar regions; alar cells strongly differentiated, when mature in excavate, brick-red groups, quadrate to rounded, ± bulging, thick-walled, not porose except those cells adjacent to supra-alar cells. Asexual propagula none. Dioicous. Perichaetia conspicuous, on branches; leaves differentiated, erect, convolute, oblong-lanceolate, 2.75-3.4 mm long, mucronate; margins bluntly serrate at apex, subentire below, ± plane throughout; costa none; cells linear, smooth, very thick-walled, with walls sometimes broader than lumina, porose; alar cells not differentiated. Setae elongate, roughened above from projecting cell ends, reddish, 1.1-1.4 cm long, curved to flexuose; capsules erect, symmetric, cylindric, 2-3 mm long; exothecial cells subquadrate, thick-walled, becoming smaller and oblate toward the mouth; annulus of 2-3 rows of small ± thin-walled cells; operculum conic-rostrate, straight, ca. 1.7 mm long; exostome teeth narrowly triangular, ± shouldered, mostly narrowly bordered, on the front surface cross-striolate below, smooth and ± perforate above (extralimitally papillose and not perforate above), slightly trabeculate at back; endostome with a very low basal membrane, segments finely roughened, linear, ± keeled, scarcely perforate, almost as long as the teeth, cilia none. Spores spherical, papillose, 22-29 µm diam. Calyptrae cucullate, densely erect- or rarely flexuose-hairy, smooth to slightly roughened at apex.
-
Discussion
1. Pilotrichella flexilis (Hedw.) Angstr., Ofvers. Förh. Kongl. Svenska Vetensk.-Akad. 33(4): 34. 1876; Leskea flexilis Hedw., Sp. Musc. Frond. 234. 1801; Hypnum flexile Sw., Prodr. 141. 1788, nom. inval, (Hedw.) Brid., Muscol. Recent. 2(2): 153. 1801; Hookeria flexilis (Hedw.) Sm., Trans. Linn. Soc. London 9: 281. 1808; Isothecium flexile (Hedw.) Brid., Bryol. Univ. 2: 361. 1827; Neckera flexilis (Hedw.) Müll. Hal., Syn. Musc. Frond. 2: 129. 1850; Meteorium flexile (Hedw.) Mitt., J. Linn. Soc., Bot. 12: 438. 1869; Pilotrichum flexile (Hedw.) Müll. Hal. ex Paris, Index Bryol., ed. 2, 4: 4. 1905, nom. inval. in syn. Plate 90, figures 1-6 Pilotrichella eroso-mucronata Müll. Hal., Bull. Herb. Boissier 5: 563. 1897; Pilotrichella erecto-mucronata Müll. Hal. ex Paris, Index Bryol. Suppl. 270. 1900, orthogr. var. Pilotrichella recurvo-mucronata Müll. Hal., Bull. Herb. Boissier 5: 563. 1897. Discussion. Pilotrichella flexilis is characterized by robust, turgid plants usually growing pendently. The stem and branch tips are obtuse or very shortly cuspidate. The leaves are broadly oblong-ovate with the apex shortly and broadly recurved-mucronate. The laminal cells are thick-walled and porose and the alar cells are strongly differentiated in brick-red, ± excavate groups. The setae are over 1 cm long and roughened above. The exostome teeth are cross-striolate below and the endostomial segments extend to about the same level as the teeth. Pilotrichella flexilis is a widespread, conspicuous species. In Hawaii it is replaced by P. mauiensis (Sull.) A. Jaeger, a slightly smaller species with even thicker-walled cells. The East African P. perrobusta P. de la Varde is even more similar to P. flexilis but differs in truncate to rounded-acute leaf apices. These are not particularly striking differences for such a variable species. However, P. flexilis may represent a complex of closely related taxa. Exostome teeth from Mexican material are decidedly papillose above with no hint of perforation. In the Greater Antilles, though, the exostome teeth are essentially smooth above and somewhat to strongly perforate. Because of the quantity of material involved, and because a revision of the group is now commencing at the Missouri Botanical Garden, a complete resolution of the problem is not possible within the context of this flora. Since the type of P. flexilis is from the West Indies, I am confident that at least our name is in no danger of change.
-
Distribution
Range. Mexico south through Central America, Colombia and Venezuela south through the Andes to Bolivia, southeastern Brazil; Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Puerto Rico, Guadeloupe; typically growing pendent from branches of trees and shrubs but sometimes creeping over wood and rock, and also persisting on humus after falling from epiphytic habitats, in humid forests, at (850-) 1200-2600 m.
Mexico North America| Central America| Colombia South America| Venezuela South America| Ecuador South America| Peru South America| Bolivia South America| Brazil South America| Cuba South America| Jamaica South America| Haiti South America| Dominican Republic South America| Puerto Rico South America| Guadeloupe South America|