Polytrichaceae 



POLYTRICHACEAE 



The Polytrichacese form a large family which has been 

 divided into some three tribes, nine genera, and about two 

 hundred species, if the plants of the whole world are considered. 



The species are often of large size and are probably the most 

 highly developed of all the mosses. One may look for the Amer- 

 ican species by roadside banks, in fields and open woods. They 

 grow in conspicuous patches and may be easily recognised by 

 their mitrate or hood-like veils, their long wiry pedicels, their 

 regularly cylindrical or angular spore-cases with mouths covered 

 by a thin membrane bordered with 32 or 64 blunt teeth, and by 

 their firm and rigid leaves with delicate vertical blades of cells 

 (lamella;) on the upper surface. 



KEY TO GENERA 



Veil. Hood-like, spore-case symmetrical or nearly so; leaves 

 wavy and crisp when dry, lamellae few (2 to 8), 

 straight, teeth 52 Catliarinca. 



Lamellae (five). 



Lamelte (two). 

 Cross sections of leaves. 



j 



P. brachyphyllitm . 

 Spore -case with 

 hairy veil. 



Pogonatum 

 tenue. Spore- 

 case, not angu- 

 lar. 



Leaf. 



Tip of spore-case; teeth 



thirty-two. 

 C. undulata. 



Veil. Mitrate, densely hairy. 



Spore-case not angular, teeth often 32 

 Spore-case 4- to 6-angled, teeth 64 . . 



239 



P. pilifcnmi. 



Spore-case 



angled. 



. Pogonatum. 

 Polytrichum. 



