BARNES — NORTH AMERICAN MOSSES. 



223 



III. Plants usually robust {4-15 cm.), rarely small, often much 

 branched above, leaves straight when dry. 



* 

 Capsule papillose, marginal cells of lamellas round in 



section P. urnigerum, 26a. 



Capsule smooth, marginal cells of lamellae ovate in section P. alpinnm,^ 263, 



POLYTRICHUM, p. 263. 



Leaves entire, margins inflexed. 



Obtuse at apex 



Aristate at apex. 

 Awn colored, short. 

 Leaves spreading when moist, subrecurved 

 Leaves erect-open, strict .... 



Awn hyaline, long 



Leaves serrate. 



Marginal cells of lamellte like rest, oval, higher 

 than broad in section. 

 Capsule ovate, obscurely angled, lid rostrate 

 Capsule oblong, 4-6 angled, lid acutely conic 

 Marginal cells of lamellas enlarged, broader than 

 high (2:1) 



P. sexangulare, S69. 



P. juniperinum,* 265. 



P. strictum, 265. 



. P. piliferum, 264. 



P. gracile, 264. 

 P. formosum,' 264. 



P. Ohioense, S70. 



Marginal cells of lamellae semilunar, with two promi- 



nent papillae at corners 



P. commune,* 266. 



P. polare C. Mull., 373; P. hyperboreum R. Br.; P. boreale Kindb.; 

 P. Icevipilum. Hpe., are not included in the key since no authentic ma- 

 terial is at hand, and the descriptions are not sufficient to determine their 

 position. The first three are arctic species and their omission is compara- 

 tively unimportant. 



BUXBAUMIA, p. 267. 



Outer peristome simple, spores 5-9//. 



Capsule little longer than broad 



Capsule much longer than broad (1 : 2-2.5) . 

 Outer peristome quadruple or triple, spores 10-16yW 



B. aphylla, 268. 

 . B. Piperi, 376. 

 B. indnsiata, 375. 



1 See Appendix, no. 366. 



* See Appendix, no. 374. 



' P. conorhynchum Kindb., evidently falls here. See Appendix, no. 368. 



* See Appendix, nos. 371, 372. 



