Pylaisia

Plants small, in low mats, yellowish to whitish, shiny. Stems creeping, regularly or irregularly pinnate, branches usually strongly curled when dry; hyalodermis absent, central strand present, small; pseudoparaphyllia foliose. Stem and branch leaves similar. Stem leaves appressed when dry, erect-spreading when moist, ovate-lanceolate, widest beyond base, not or slightly plicate; base not or weakly decurrent; margins plane, sometimes slightly involute distally, subentire to serrulate distally; apex acuminate; costa double and short or indistinct; alar cells differentiated, subquadrate to rectangular; laminal cells smooth; distal cells usually longer than 6:1. Branch leaves narrowly ovate- to oblong-lanceolate, smaller to occasionally somewhat larger than stem leaves. Specialized asexual reproduction absent. Sexual condition autoicous; inner perichaetial leaves erect, oblong-lanceolate, apex subulate. Seta yellowish or reddish. Capsule erect to suberect, oblong-cylindric to oblong-ovoid, straight, not contracted below mouth; annulus differentiated or not; operculum conic to rostrate, obliquely short- to long-acute or obtuse; peristome perfect to reduced, hygroscopic; exostome teeth with external surface smooth basally, sometimes roughly papillose distally; endostome basal membrane present, segments sometimes 2-fid or fragmentary, keeled, cilia rudimentary. Calyptra naked. Spores spheric [somewhat tetrapozoidal by endosporic protonemata], finely papillose.

Distribution

North America, Mexico, Central America, South America (Andes Mountains), Europe, Asia.

Discussion

Species 16 (4 in the flora).

Pylaisia has yellowish brown stems 2 cm long and reddish capsules; the exothecial cell walls are thin. The setae are sinistrorse-twisted basally and dextrorse-twisted distally when dry; the capsules have few phaneropore stomata on the base of the neck; and the exostome teeth are lance-subulate to blunt, distinctly lamellate, and internally trabeculate.

Selected References

Arikawa, T. 2004. A taxonomic study of the genus Pylaisia (Hypnaceae, Musci). J. Hattori Bot. Lab. 95: 71–154.

Lower Taxa

Pylaisia intricata, Pylaisia polyantha, Pylaisia selwynii, Pylaisia steerei

Key

1	Endostome free, segments neither 2-fid nor perforate; spores usually smaller than 16 µm; stem leaves usually longer than 1.3 mm	> 2
1	Endostome wholly or partially adherent to exostome teeth, segments split, 2-fid; spores usually larger than 16 µm; stem leaves usually shorter than 1.2 mm	> 3
2	Branches subjulaceous; stem and branch leaves slightly differentiated; alar cells 8-10 along margins; endostome 0.3 mm beyond mouth.	Pylaisia polyantha
2	Branches ± complanate-foliate, partly subjulaceous; stem and branch leaves well differentiated; alar cells 10-15 along margins; endostome 0.4-0.5 mm beyond mouth.	Pylaisia steerei
3	Endostome free distally; stems regularly pinnate; alar cells 20-25 along margins.	Pylaisia selwynii
3	Endostome wholly adherent; stems irregularly pinnate; alar cells 6-12 along margins.	Pylaisia intricata