Hair-cap Mosses 



P. Alpinum Leaf 

 with serrate mar- 

 gin and numerous 

 lamellae, 



P. brevicaule. 

 Stem with peri- 

 chaetial leaves. 



P. brevicaule. 



Spore-case with 

 veil. 



P. brevicaule. Top of spore-case with 32 teeth 

 united by their tips to a membrane. 



nearly symmetrical, erect, or 



turned to one side, with flat 



lids having a central point. They 



are borne on erect pedicels. 



The peristome is simple, of 



32 blunt teeth, orange in the 



middle, united at the base and 



appearing as if attached at the 



apices to a membranous disk 



(epiphragm) . 



There are one hundred and 



fifty-six species known in all, 



nine in North America. 



The Short-stemmed Hair- 

 cap Moss, Pogonatiim brevi- 

 caule, Beauv. See Colour Plate 



IV. 



Habit and habitat. The short- 

 stemmed Pogonatiim is remarkable 

 because of its habit of retaining the 

 protonema, which persists as a 

 bright-green felt covering the 

 ground at the base of the plants. 

 It binds the crumbling earth so that 

 one may gather it in sheets. As 

 the moss commonly grows in clay- 

 banks, in ditches, and in places 

 rather insecure, it may be that the 

 habit of retaining the protonema 

 has been evolved in the struggle for 

 existence to enable it to live in situ- 

 ations too insecure to be occupied by other mosses 

 243 



P. urnigcrnm. 



Spore-case with 

 lid. 



P. brevicaule. 

 Spore-case with 

 lid. 



