OF WESTERN' PENNSYLVANIA 91 



2. WEISIA Hedwig. 



Autoicous, rarely paroicous, polyoicous, or dioicous : low, 

 cespitose, freely branching : upper leaves much larger, relative- 

 ly to the lower, erect-spreading, crisped when dry, carinate, 

 elongate-lanceolate ; costa strong, cuspidate-excurrent ; basal 

 leaf-cells rectangular, hyaline, the upper small, rounded, low- 

 papillose on both surfaces : seta erect or sometimes curved, 

 mostly longer than the perichaetial leaves ; capsule erect and 

 symmetric or a little inclined and swollen dorsally, round-ovate 

 to cylindrical, narrow-mouthed, finally usually somewhat 

 plicate, the urn at the rim being several cells thick and the 

 insertion of the peristome thus considerably removed from the 

 exterior border of the rim ; peristome-teeth short, often rudi- 

 mentary, undivided, papillose, the exterior layer more strongly 

 developed and with projecting bars ; lid obliquely long-rostrate ; 

 calyptra cucullate. 



A widely distributed genus of 27 terrestrial species ; 6 

 species occurring in North America ; only one in our range. 



1. Weisia viridula | Linnaeus] Hedwig. 



(Bryum mridulum Linnaeus). 



(Plate XII) 



Densely cespitose, yellowish-green : stem erect, often 

 branching, up to 5 mm. tall ; leaves erect-spreading, the upper 

 much larger and up to 3 mm. long and 0.5 mm. wide, lance- 

 linear, tapering to an acute or acuminate apex, the margin 

 strongly involute, entire, leaves crispate when dry ; costa 

 strong, about .030-.040 mm. wide at base, excurrent into a 

 short and more or less hyaline point ; upper leaf-cells roundish- 

 hexagonal, strongly papillose, obscure, the basal more or less 

 elongate-rectangular and hyaline : seta slender, up to 1 cm. 

 long, lustrous, yellowish, faintly sinistrorse ; capsule erect, 

 ovoid, symmetric, slightly narrowed at mouth, reddish-brown, 

 about 0.9 mm. long, somewhat plicate when dry and empty; 

 exothecial cells rather thin-walled, irregularly oblong to hexa- 

 gonal or rounded, those at the mouth in 3-5 rows, much 

 smaller, quadrate and darker in color ; peristome-teeth more or 

 less rudimentary, short, irregularly linear, divided, or truncate, 

 papillose ; lid conic, obliquely long-rostrate, altogether nearly 

 as long as the urn ; calyptra cucullate, covering about two- 

 thirds of the capsule; spores orange-pellucid, papillose, about 

 .016-.019 mm. in diameter, mature in spring. 



Almost cosmopolitan on bare earth in fields, excavations, 

 along roadsides, etc. Rather uncommon in our region. 



Favette : Ohio Pyle, on clay bank, September i 3, 1906. 

 O. E. J. and G. K. J. (Figured.) 



