Pseudotaxiphyllum Z. Iwatsuki, J. Hattori Bot. Lab. 63: 448. 1987.
[Greek pseudo, false + Taxiphyllum, a genus of mosses in the Hypnaceae]
Robert R. Ireland
Plants medium-sized, in thin to dense, often complanate, light- to yellowish-green, dull to glossy mats. Stems 1.5--3.5 cm, creeping, simple or sparingly and irregularly branched, cortical cells small, thick-walled, central strand sometimes present; rhizoids smooth, in clusters proximal to leaf insertions; axillary hairs not observed; pseudoparaphyllia lacking. Leaves of stem and branches similar, somewhat rigid, crowded and imbricate, erect-spreading to squarrose, sometimes upturned-homomallous, often complanate, smooth or undulate, flat or concave, symmetric to asymmetric, not decurrent, lanceolate, ovate, ovate-lanceolate or oblong-lanceolate, acute, sometimes abruptly so, to acuminate; margins plane to erect, serrate to serrulate; costa short and double or lacking; cells firm-walled, often flexuose, linear-fusiform, smooth, walls not pitted; alar regions not or distinctly differentiated with numerous quadrate to short-rectangular cells. Specialized asexual reproduction by multicellular bodies sometimes present in clusters at stem apices or below in leaf axils, elongate, smooth-celled, twisted-vermiform, with 1--5 acute teeth, 0.1--0.5 mm, or resembling parent plant but smaller, bearing reduced leaves from apex to base of propagula, 0.5--1.5 mm. Sexual condition dioicous or sometimes autoicous, usually sterile; perigonia along stems, perichaetia at base of stems, bracts small, lanceolate to ovate, acuminate to abruptly filiform-acuminate, margins plane. Seta smooth, elongate, straight or sometimes curved, twisted, red to reddish brown. Capsule cernuous to pendulous, straight to subarcuate, dark brown to dark red, smooth to wrinkled, contracted below mouth and wrinkled at neck when dry; opercula conic to short-rostrate, shorter than urn; annulus present, deciduous, of 2–3 rows of cells; peristome double, exostome teeth cross-striolate proximally, papillose distally, bordered, trabeculate on interior; endostome with a high to low basal membrane, keeled segments and cilia shorter than the segments, in groups of 1--3. Calyptra cucullate, smooth, naked. Spores spherical to ovoid, minutely papillose.
Species 10 (3 in the flora): North America, Central America, South America, Europe, Africa, Asia.
Plants of this genus occur in terrestrial habitats in temperate, subtropical and tropical regions.
SELECTED REFERENCES
Ireland, R.R. 1969. A taxonomic revision of the genus Plagiothecium for North America, north of Mexico. National Museums of Canada, Nat. Mus. Nat. Sciences, Publs. in Botany, No. 1: 1--118. Iwatsuki, Z. 1987. Notes on Isopterygium Mitt. (Plagiotheciaceae). J. Hattori Bot. Lab. 63: 445--451.
OTHER REFERENCES
Redfearn, P.L., Jr. 1973. Additions to the moss flora of Texas, and a new species of Isopterygium. Bryologist 76(3): 440--442.
