POLYTRICHACEAE 167 



h. I 



Polytrichum alpinum var. arcticum (Sw.) Wahl. 

 {Pogonalum alpinum var. arcticum (Sw.) Brid.) (Plate 

 VII, Fig. 9) is found in mountainous or hilly regions 

 and along the coast. The stems are up to 3 inches long, 

 often slightly branched; the leaves are a rather dark 

 green; the margins are not folded in; the capsule is 

 cylindrical, slightly inclined and curved when mature; 

 the operculum is long-beaked; and the calyptra only 

 partly covers the capsule. 



Range, northern part of North America and northern 

 Europe. 



This species is not to be expected except in the 

 higher altitudes. It is distinguished from other Poly- 

 trichums when in fruit by the cylindrical capsule, and 

 from the Pogonatums by the larger size, and larger, 

 curved capsule. See p. 160. 



h. 2 



Polytrichum ohioense Ren. & Card. (Plate VII, 

 Fig. 7) is a common species. The stems are up to 3 

 inches long; the leaves are olive or dark green; the 



leaf-margins are not folded in; the capsule is angled, 

 gradually tapering to the seta; the seta is usually reddish 

 below and yellow above; the operculum has a beak of 

 medium length, longer than in P. commune, but not 



