Jennings: Manual of Mosses — 2. Dicranaceae 65 



Key to the Species 



A. Leaves smoothish to serrulate not over half-way down B. 



A. Leaves serrulate to well below the middle (D. asperulum) 



B. Peristome-teeth cleft to the base; leaves with somewhat widened aurirles 



\. D. denudatum 



B. Peristome-teeth not cleft to base; leaves not auriculate C 



C. Leaves easily caducous; seta 1.5-2 cm; urn L5-2 mm long 2. D. virginkum 



C. Leaves rather persistent; seta 5-8 mm; urn 1 mm long 3. D. Miltspaughu 



\. Dicranodontium denudatum (Bridel) E. G. Britton 



(Didymodon longirostris Starke) 

 Plate XIII 



Densely and. softly cespitose, lustrous, pale green, when dried as in her- 

 barium-specimens often a lustrous yellowish-brown: stems erect or ascending, 

 up to 3 or 4 cm high, forking frequently, flexuous, radiculose below; leaves 

 rather numerous, often quickly deciduous, from a more or less sheathing oblong 

 concave base with more or less widened auricles gradually narrowed to a long, 

 flexuous-spreading or falcate-secund, linear-subulate or setaceous, tubulose 

 point, the margin entire to faintly denticulate towards the apex; costa strong, 

 one-fifth to one-third the width of the leaf at base, excurrent in the rough 

 subulation, in cross-section showing a median row of large hyaline cells bor- 

 dered on either side by minute incrassate cells; alar leaf-cells large, inflated, 

 hyaline to brownish, rectangular, above becoming incrassate and narrower, in 

 the oblong base the upper marginal cells elongate-linear and more or less 

 prosenchymatous, the median and upper rounded-quadrate, varying to short- 

 rectangular or oblong: seta cygneous, dextrorse; capsule oblongcylindric, small; 

 peristome-teeth cleft to the base or nearly so into two filiform divisions, in- 

 serted below the mouth of the urn, reddish; lid as long as the urn, subulate- 

 rostrate, i>traight; spores mature in late fall or in winter: dioicous. 



On sandstone rocks, walls, turfy places, etc., usually in hilly or mountain- 

 ous regions. Europe, Asia, and, in North America, from New Brunswick and 

 Alaska south to Ohio and Pennsylvania. 



Rare and usually sterile in our region, often on the vertical face of heavy conglomerate 

 boulders. Fayette Co.: Mouth of Cucumber Run, Ohio Pyle. C.M.B. June 22 and 

 Oct. 20. 1940. Forest Co.: Vertical face of s.s. block. Blue Jay Creek, 1 mi. n. of 

 Frost. C.M.B. May 28, 1946. McKean Co.: Rutherford Rocks, July 7. 1894. Haw- 

 kins, October 18, 1895, Langmade Rocks, April 16, 1896, all in the vicinity of Bradford. 

 D.A.B. (figured). Somerset Co.: Face of dry rock, Beck Spring, Laurel* Mt. C.M.B. 

 July 26, 1947. 



2. Dicranodontium virginicum E. G. Britton 



Lustrous, bright green: stems ascending to erect, below red-tomentose; 

 leaves erect-spreading to secund, variously straight to curled or twisted, often 

 5 mm. long, narrowly concave-subulate from a short, thick, non-auriculate 

 base, often caducous, the caducous leaves usually with smooth points, the per- 

 sistent ones with serrulate points; alar cells more or less hyaline, the median 

 and upper rectangular to quadrate, incrassate; seta appearing lateral by growth 

 of innovations, flexuous, up to 2 cm long, lustrous, yellow, arcuate to erect; 



