Taxiphyllum

• Authority

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

• Family

  Hypnaceae

• Scientific Name

  Taxiphyllum

• Description

  Genus Description - Plants mostly medium-sized, in often lustrous, mostly soft, green to yellow-green, sometimes brown-tinged, often extensive, thin to dense, loose, flat mats. Stems creeping, sparingly and irregularly branched, rarely unbranched, often complanate-foliate; in cross-section without a hyalodermis, with small thick-walled cells surrounding larger thinner-walled cells, central strand present or absent; pseudoparaphyllia foliose; axillary hairs with 1-2 short brown basal cells and a single elongate hyaline distal cell. Stem and branch leaves mostly similar, occasionally differentiated, imbricate to distant, often complanate, erect-spreading to squarrose, ± symmetric, ovate to narrowly oblong, usually acute to short-acuminate, rarely obtuse, often concave, rarely subplicate, not decurrent; margins serrate to serrulate above, entire to serrulate below, plane or recurved; costa short and double or absent; cells linear to linear-flexuose, smooth or prorulose at upper ends at back, mostly thin- to firm-walled, not or scarcely porose, typically shorter in the apex, becoming rectangular in a few rows across the insertion; alar cells mostly few in extreme angles, quadrate to short-rectangular. Asexual propagula not seen. Dioicous or rarely synoicous. Perichaetial leaves erect, lanceolate to ovate-lanceolate, gradually to abruptly acuminate; margins serrulate above, serrulate to entire below, plane to erect or recurved; costa usually none; cells linear, smooth or rarely prorulose, thin- to thick-walled, becoming shorter and broader toward the insertion; alar cells not differentiated. Setae elongate, smooth, yellow-brown to reddish, twisted; capsules inclined to pendent, straight to arcuate, asymmetric, ovoid to short-cylindric; exothecial cells ± isodiametric, thin- to firm-walled, sometimes collenchymatous; annulus differentiated; operculum rostrate, usually oblique; peristome double, exostome teeth shouldered, bordered, on the front surface cross-striolate below, papillose above, trabeculate at back; endostome with a high basal membrane, segments keeled, not or narrowly perforate, ca. as long as the teeth, cilia in groups of 2-4. Spores spherical, smooth to finely papillose. Calyptrae cucullate, naked, smooth.

• Discussion

  Taxiphyllum M. Fleisch., Musci Buitenzorg 4: 1434. 1923; Plagiothecium subgen. Taxiphyllum (M. Fleisch.) Grout, Moss Fl. N. Amer. 3; 161. 1932. Discussion. Taxiphyllum is characterized by complanate, lustrous plants with foliose pseudoparaphyllia and a small, thick-walled stem cortex. The leaves are not decurrent, usually serrulate, typically with short apical cells, and sometimes with laminal cells prorulose at back from projecting upper ends. The plants are dioicous and rarely fertile. Although Fleischer (1923) described Taxiphyllum, it was Iwatsuki (1963b) who defined the genus in the modem sense by correlating leaf characters with pseudoparaphyllia and stem anatomy. Ireland’s (1969) treatment of the North American taxa is useful even though the overlap of North American and West Indian taxa is minimal. Robinson’s (1974) consideration of the generic definition of Taxiphyllum can also be consulted although it does not directly affect our flora.