OF WESTERN PENNSYLVANIA 95 



South America, and. in North America, from Greenland to 

 Manitoba and southward in the mountains to North Carolina. 

 Rare in our region. 



Huntingdon: Alexandria. Porter. (Porter's Catalogue). 



McKean : Toad Hollow, Bradford, July 19, 1896. Sterile. 

 D. A. B. (Figured). 



6. TORTELLA (C. Mueller) Limpricht. 



Dioicous ; rarely autoicous : widely and deeply cespitose, 

 the cushions often yellowish-green outside, brownish inside : 

 stem erect, mostly without a central strand, felted-radiculose : 

 leaves tufted at the apex of the stem, widely spreading to re- 

 curved-squarrose from a whitish and shining base, cirrhate- 

 crispate when dry, elongate-lanceolate to subulate, margin un- 

 dulate, entire, usually involute above; costa strong, ending 

 in the apex or excurrent ; basal leaf-cells differentiated, hyaline, 

 elongate-rectangular, extending up the margins, smooth ; upper 

 cells green, small, rounded-quadrangular, thickly papillose on 

 both sides : seta red, long, erect ; capsule erect to inclined, 

 oblong to cylindric ; annulus rarely differentiated ; peristome 

 attached below the rim of the urn, the basal membrane low, 

 teeth 2i2. filiform, sinistrorsely wound, papillose ; spores small ; 

 lid small and elongate-conic ; calyptra cucullate, smooth, long- 

 rostrate. 



A cosmopolitan genus, the 33 species mainly occurring on 

 soil or on rocks ; 5 species in North America ; 2 in our region. 



Key to the Species. 



a. Dioicous: leaves long-acuminate. i. T. tortuosa. 



a. Autoicous: leaves linear-lanceolate to oblong-lanceolate, costa 

 shortly excurrent as an abrupt mucro. 2. 7". humilis. 



1. Tortella tortuosa [Linnaeus] Limpricht. 

 {Barhila tortuosa Weber and Mohr ; Tortula tortuosa Ehrhart). 

 Densely cespitose in rounded tufts, yellowish or pale green 

 above, brownish below : stems stout, branching, up to 6 cm. 

 high, red-brown-radiculose ; leaves crowded, usually 4-6 mm. 

 long, lance-linear, tapering to a gradually acuminate apex, 

 flexuous-spreading, margin crenulate-papillose, more or less 

 vmdulate, plane at the apex ; leaves when dry strongly crispate- 

 contorted ; costa strong, pale, excurrent into the fine and some- 

 times denticulate acumen ; basal leaf-cells thin-walled, hyaline, 

 extending obliquely up the margin, above becoming abruptly 

 smaller, chlorophyllose, rounded, incrassate, papillose : seta 

 1-3 cm. long, reddish below, paler above ; capsule cylindric, 

 2.5-3.5 mm. long, usually somewhat curved, almost erect; lid 

 obliquely and slenderly conic-rostrate, at least one-half as 

 long as urn ; peristome-teeth long and from a low basal mem- 



