POTTIACEAE 105 



Didymodon is to be expected on the hills and moun- 

 tains of limestone regions. The conspicuous charac- 

 teristic is the rusty-red color of the lower leaves, which 

 distinguishes this species from other mosses of the 

 same locality. 



15. BARBULA Hedw. (Bar-bu-la) 



A large genus widely distributed. But two species 

 are described here and they are not common. Name 

 derived from the Latin for ''beard," referring to the 

 peristome. 



Barbula unguiculata (Huds.) Hedw. is found on the 

 ground and on stones; sometimes on stone 

 walls. 



Barbula convoluta Hedw. grows on the 

 ground in rather dry places. 



Plants growing close together; yellow-green; Barbula 

 fruit often abundant. unguiculata 



Stems erect, short, usually less than }^ inch laJgeT" 

 long. 



Leaves^ if large enough to be seen, short and hair-like; 

 much crisped when dry. 



Seta about >^ inch long; reddish-brown in B. unguiculata; 

 yellowish in B. convoluta, becoming reddish with age. 



Capstde long-cylindrical , erect. 



Peristome twisted as in Tortclla (p. 102), and Tartula 

 (p. 107). 



Operculum long-beaked. 



Range, Canada and the northern and western United 

 States; Europe; Asia; Africa. 



