OF WESTERN"- PENNSYLVANIA 117 



McKean : Quintuple, Bradford, November 10, 1893. 



D. A. B. 



Washington : Linn and Simonton. i Porter's Cata- 



O 



logue), 

 3. ORTHOTR1CHUM Hedwig. 



Autoicous, rarely dioicous : cespitose in cushions some- 

 times on rocks, mostly on trees : stems erect and ascending, 

 radiculose at the base, thickly leaved, branched; leaves when 

 dry never crispate but straight and appressed, ovate-or linear- 

 lanceolate, mostly acute, margins usually revolute ; costa quite 

 strong, mostly not quite percurrent ; basal leaf-cells rectangular 

 to elongate, pellucid to hyaline, the marginal often shorter 

 and green : seta generally shorter than the scarcely or non- 

 sheathing perichaetial leaves ; capsule oval to cylindric, usually 

 with 8 or 16 colored stride, when dry usually 8 (16) -furrowed; 

 annulus persistent ; peristome mostly double, sometimes single, 

 rarely none, usually with 16 broadly lanceolate teeth in pairs, 

 and 8 to 16 filiform segments ; operculum conic to convex, 

 rostrate ; calyptra campanulate, plicate, covering most of the 

 urn, glabrous, hirsute or papillose. 



A cosmopolitan genus of about 206 species, on trees or 

 rocks, rare, however, in the Tropics; about 70 species occur 

 in North America ; at least 5 in our region. 



Key to the Species. 



a. Peristome simple, teeth 16, erect or erect-spreading when dry. 



b. 

 a. Peristome double, teeth more or less reflexed when drv. 



d. 



b. Capsule half-emergent, 16-striale. (O. cupulatuni i Hoff- 



mann] Schwaeg- 

 richen.) 

 b. Capsule immersed to half-emergent, 8-striate. 



c. 

 c. Capsule ovate-cylindric, half-emergent when leaves are dry. 



i. O. strangulatain. 



c. Capsule much shorter, ovate-globose, practically immersed in the 

 dry leaves. 2. O. Icscitrii. 



d. Capsule smooth when dry, immersed, e, 

 d. Capsule plicate when dry. f. 



e. Teeth 16, in pairs: segments 8, short, liliform. 



(O. pnsilliiin Mitten.) 

 e. Teeth 16, not in pairs: segments 16, comparatively broad. 



(O. leiocarpnm Bryolo- 



gia Europaea.) 

 f. Leaves more or k-s> ubtu>e at the extreme ap^-x. 



g- 



f. Leaves usually distinctly acute at the extreme apex. 



i. 



g. Capsule strongly contracted below the mouth when dry and very 

 decidedly plicate with reddish-brown folds. 



3. O. bra-it nil. 



