THE POLYTRICHACE^ OF WESTERN NORTH AMERICA 313 



Fig. 20. Poljrtrichum ohioense. 



1 = Moist plant with capsule, X i. 2 = Dry plant, X i. 3 = Capsule, X 5- 4 = 

 Immature capsule with calyptra, X 5. 5 = Peristome, X 150. 6 = Leaf showing 

 lamellas on upper side, X 15. 7 = Leaf tip, X 65. 8 = Cross section of leaf showing 

 lamellae, X 65. 9 = Cross section of a few lamellae showing usual form of marginal 

 cells, X 250. 10 = Cross section of a few lamellae just above sheath, X 250. 



and distinctness of the hj-pophysis. However, all the specimens examined could at 

 once be distinguished by the marginal cells of the lamelke. Occassionally in P. ohioense 

 they are somewhat depressed in the center approaching forms of P. Commune but the 

 elongated capsule clearly separates it from the last. P. ohioense tends to have fewer 

 lamellae than P. allennalum; of the specimens examined none of the former had over 

 45, while none of the latter had less than 45. 



