Jennings: Manual of Mosses — 5. Pottiaceae 83 



slender, erect, about 1.5 mm long, yellow; capsule linear-cylindric, brownish; 

 lid conic and obliquely rostrate; peristome-teeth short, untwisted, linear-subu- 

 late, fragile, usually more or less irregularly cleft or perforate; spores about .012 

 mm in diameter, mature in autumn: dioicous: fruit produced but rarely. 



On wet non-calcareous stones in brooks or at the base of cliffs in hilly or 

 mountainous districts, in Europe, Asia, South America, and, in North Amer- 

 ica, from Greenland to Manitoba and southward in the mountains to North 

 Carolina. 



Rare in our region. Huntingdon Co.: Alexandria. Porter. (Porter's Catalogue). 

 McKean Co.: 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, brov/nish inside: stem erect, mostly without a central 

 strand, felted-radiculose: leaves tufted at the apex of the stem, widely spreading 

 to recurved-squarrose from a whitish and shining base, cirrhate-crispate when 

 dry, elongate-lanceolate to subulate, margin undulate, entire, usually involute 

 above; costa strong, ending in the apex or excurrent; basal leaf-cells differen- 

 tiated, hyaline, elongate-rectangular, extending up the margins and forming a 

 Y-shaped area, 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 32, filiform, sinistrorsely wound, 

 papillose; spores small; lid small and elongate-conic; calyptra cucullate, smooth, 

 long-rostrate. 



A cosmopolitan genus, the 37 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 1. T. tortuosa 



A. Autoicous: leaves linear-lanceolate to oblong-lanceolate, costa shortly excurrent as an 



abrupt mucro 2. T. humilis 



1. Tortella tortuosa [Linnaeus] Limpricht 



(Bar bill J tortuosa Weber and Mohr; Tortula tortuosa Ehrhari) 



Densely cespitose in rounded tufts, yellowish or pale green above, brown- 

 ish 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 

 undulate, plane at the apex; leaves when dry strongly spirally crispate-con- 

 torted; costa strong, pale, excurrent into the fine and sometimes denticulate 

 acumen; basal leaf-cells thin-walled, hyaline, extending obliquely up the mar- 



"^ Tortella nitida (Lindb.) Brotherus, with leaves (when dry) curling in circles at the 

 tip and with the costa lustrous dorsally; and also T. fragilis (H. & W. ) Limpricht, with 

 leaves curled only slightly at the tip when dry and frequently broken off, may be expected 

 in the northern part of our range. 



