288 FRYE 



PSILOPILUM Brid. 



Name derived from psilos = bare, and pilos = felt; referring to 

 the absence of felted or matted hairs on the calyptra. 



Plants dioicous. Stems simple, from subterranean shoots. 



Leaves keeled or incurved, lanceolate or ligulate, not undulate, 

 never toothed at back, i cell thick, when moist more or less patent 

 from an indistinct sheath, when dry appressed or the tips incurved. 

 Margin not bordered. Lamellae on upper side only, wavy from side 

 to side, with crenulate edges; marginal cells similar to the others. 

 Cells quadratic or round-hexagonal, rectangular at base. 



Calyptra cucullate, naked, or at tip papillose. 



Capsule usually inclined, more or less distinctly obliquely ovate, 

 with small mouth, laterally compressed, smooth, with large 2-celled 

 stomates. Peristome present (in North American species); teeth 

 usually unequal in size. Lid easily falling off, pointed to long and 

 thinly rostrate from a conic base. Pedicels single. 



Number of species in western North America, i ; total number spe- 

 cies, about 13. 



1. Psilopilum glabratum (Wahl.) Holz., in Bryologist, 5: p. 80 



(1902). 



Oligotrichum glabratum (Wahl.) Lindb., in Muse. Scand. p. 12 (187 9). 

 Psilopilum tschulschicum 8 (C. M.) Par., in Index, ed. i,p. 1040. 



(1897). 



Psilopilum arcticum Brid., in Bryol. Univ. Vol. 2, p. 96 (1827). 



Name from glabrare = to deprive of hair; referring to the smooth 

 calyptra. 



Stem 1 3 cm. high. 



Leaves very concave, muticous. Margin irregularly crenuiate 

 above. Lamellae 7 10, disappearing toward the base. Vein van- 

 ishing in the apex, smooth on the back. Cells small, long-rectangu- 

 lar at the base. 



Calyptra very narrow, smooth. 



Capsule ferruginous, black when old, ovate-gibbous. Teeth long, 

 some of them 2-parted, thin. Lid short, convex-conic, with short 

 incurved beak. Pedicel terminal, erect, brownish, .5 1.5 cm. long. 



8 Cardot & Theriot in Proc. Wash. Acad. Sci. 4, p. 327 (1902). 



