Mosses and Lichens 



The spores small and smooth. 



There are ninety-nine species in all, about fifteen of them 

 known in North America. 



Genus POLYTRICHUM 



KEY TO SPECIES 



I. Leaves entire, margins inflexed, 

 apex obtuse, P. sexangulare. 



Apex rough-awned. 



Awn coloured brown or red, 

 short. Leaves spreading 

 when moist, somewhat re- 

 curved . . P. funiperinum. 



Awn whitish, transparent, 



long P. piliferum. 



II. Leaves serrate. 



Marginal cells of lamellae not 

 enlarged in section, higher 

 than broad. 



Spore-case egg-shaped, ob- 

 scurely angled. 



Lid beaked P. gracile. 



Spore-case oblong, 4- to 6- 

 angled. 



Lid acutely conic, P. formosum. 



Marginal cells of lamellae en- 

 larged, broader than high, 

 2 to i P- Ohiense. 



Marginal cells of lamellae semi- 

 lunar, with two prominent 

 horns at corners, P. commune. 



P. sexangulare. 

 Leaves. 



P.jimipcriniun. 

 Leaf. 



P. piliferum. 

 Leaf. 



P. Ohiense. 



P. commune. 



P. commune. 

 Leaf. 



Vertical rows of cells from lamella. 

 (a) Terminal cell broader than 

 high; (6) terminal cell semilunar. 



250 



P. gracile. 

 Spore-case. 



