BARNES — NORTH AMERICAN MOSSES, 203 



ORTHOTRICHUM, p. 164. 

 I. Stomata superficial. 



I. Peristome simple. 



Capsule entirely smooth. 



Wholly exserted 0. laevigatum, 165. 



Immersed 0. Schlotthaueri, 218. 



Capsule strongly costate. 

 Leaves densely papillose. 

 Capsule wholly exserted, abrupt at base, teeth 8 0. Douglasii, 167. 

 Capsule immersed or emergent, defluent into seta, teeth 16. 

 Leaf bistratose in the upper part ... 0. Sturmii, 166. 



Leaf unistratose 0. rhabdophorum, 227. 



Leaves almost smooth 0. bullatum, 222. 



Capsule ribbed only near the mouth. 

 Teeth striolate, capsule exserted .... 0. Roellii, 217, 

 Teeth papillose, capsule immersed , . . .0. Shawii, 213. 



2. Peristome double. 



[OO. IcBvigatuni, Sturmii, Jtoellii and Schlotthaueri may be sought here.] 



a. Capsule entirely smooth. 



Immersed, papillae simple ..... 0. striatum,^ 174. 

 Exserted, papillae bifurcate. 

 Alar cells thick walled, quadrate to hexagonal 0. arcticum, 228. 



Alar cells not thickened, rectangular. 

 Leaf margin revolute, capsule cylindrical when 



moist 0. Macounii, 228a. 



Leaf margin reflexed, capsule obovate when moist 0. Kingianum, 170. 



b. Capsule strongly costate. (c) 



Leaves beset with clavate gemmae, teeth reflexed, cilia 16 0. Lyellii,^ 177. 

 Leaves not gemmiferous. 

 Teeth erect when dry, cilia 16 .... 0. Texanum, 166. 

 Teeth reflexed when dry, cilia 8. 

 Cilia of two rows of cells, broad. 

 Leaf margins plane, cilia broad throughout 0. obtusifolium, 177. 

 Leaf margins revolute, cilia broad at base . 0. sordidnm, 170. 



1 O. leiocarpum B. & S. 

 ^ See Appendix, no. 221. 



