OF WESTERN PENNSYLVANIA 117 



AIcKean : Quintuple, Bradford, November 10, 1893. 



D. A. B. 



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

 logue). 



3. ORTHOTRICHUM 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 wrhen 

 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 lea\es ; capsule oval to cylindric, usually 

 with 8 or 16 colored stria, when drj' 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 dr3'. 



d. 

 b. Capsule half-emergent, 16-striate. (O. cupulatuin [Hoff- 



mann] Schwaeg- 

 richen.) 

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



c. 

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



r. O. strangulatwu . 

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

 dry leaves. 2. O. lescuril. 



d. Capsule smooth when dry, immersed, e. 

 d. Capsule plicate when dry. i. 



e. Teeth 16, in pairs; segments 8, short, filiform. 



(O. pusilluin Mitten.) 

 c. Teeth 16, not in pairs; segments 16, comparatively broad. 



(O. leiocarpuiii Bryolo- 

 gia Europasa.) 

 f. Leaves more or less obtuse at the extreme apex. 



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. byautiii. 



