OF WESTERN PENNSYLVANIA 287 



McKean : East Branch, Teina Swamp, north of 



Bradford, January 18, 1895. D. A. B. 



Snyder : In bog between Shamokin Dam and Rich- 



field, July 17, 1908. O. E. J. (Figured). 



9. HYGROHYPNUM Lind)aerg. 



Autoicous or dioicous: slender to robust, in flattish or 

 cushion-like tufts, lustrous, green to yellowish-green or golden- 

 green: stem long, procumbent, with few or ho rhizoids, re- 

 motely and irregularly branched ; leaves spreading to secund 

 or imbricate, concave, smooth to weakly plicate, more or less 

 decurrent, lance-ovate, and acuminate or broadly oval and 

 obtuse to rounded, sometimes almost orbicular, margins plane, 

 entire or serrate ; cost^ mostly unequally forked, short, weak, 

 rarely simple and long ; leaf-cells to the base uniformly narrow- 

 ly linear-vermicular, mostly with obtuse ends, smooth, the 

 apical often shorter and rhombic, the basal yellow to orange, 

 the alar portions little or not excavate but with wider, quadrate 

 to rectangular, hyaline to colored cells forming a sinall but 

 often well-defined auricular group ; inner perichsetial leaves 

 erect, elongate, plicate, costa simple or forked, short : seta 

 long, reddish, drying flattened and twisted ; capsule inclined 

 to horizontal, mostly oval to ob}ong, dorsally gibbous, drying 

 arcpate and mostly constricted bplow the mouth, annulate; 

 peristome normally hypnoid ; lid convex-conic. 



A genus of about 20 species in wet or moist places in cool 

 regions. ; in North America about 12 species ; in our region at 

 least 2 species, probably another to be expected. 



Key to the Species. 



a. Leaves falcate. J. H. luridum. 



a. Leaves not falcate. b. 



b. Costa very short, double, or forked, or none. 



2. H. eugyriuin. 

 b. Costa reaching mjddje of leaf. (H. ochraceum (Turn- 



er) Brotherus). 



1. Hygrohypnum luridi^m [Hedwig] New Combination. 

 {Hypnniit paliistre Hudson; Amblystegium palustre L,indberg; 

 Hypnnm luridum Hedwig; CaUiergon palustre Kindberg). 



Yellowish-green, or dark-green, irregularly cespitose in 

 low patches : stems denuded below, long, divided irregularly, 

 the branches erect to ascending, often more or less hooked at 

 the tip ; leaves close, either imbricated or more or less falcate- 

 secund, always concave, the margins incurved towards the 

 summit, oval- to ovate-oblong, entire, about \-\.S mm. long, 

 the apex variably, either ohtuse or acute or rounded and 

 apiculate; costa usually single or forked and reaching about 

 half way up the leaf, but variable; leaf-cplls rather lax, atjput 

 5-10:1, usually linear-rhomboid, rather opaque, somewhat 



