BRYACEAE 129 



by far much more common than Bryum, and therefore 

 more frequently collected. It grows in larger patches 

 and fruits more abundantly. The red stems are not 

 conspicuous and can be seen in the taller plants only by 

 holding them in a good light; the young, sterile growth 

 shows this characteristic as well as any. The leaves at 

 this stage are lighter green than in the older plants. 

 For comparison of sterile growth with another common 

 moss see under Ceratodon (p. 83). 



28. BRYUM Dill. (Bry-um) 



A widely distributed genus of several hundred spe- 

 cies, only a few of which are fairly frequent. Name 

 derived from the Greek for some Crypto- ^^ 

 gamic plant. 



Plants growing close together on the ground 

 or on rocks, rarely on decaying wood; yellow- 

 ish-green to dark green, sometimes brown- I '^^\ 

 ish; silvery in B. argentcum; fruit sometuncs 

 abundant. 



Stems erect; about ^ inch long except in ^^ 

 B. bimum, when they may reach 2 inches; ^ 

 often reddish; somewhat branched. Bryum 



Leaves erect or spreading, about four to five catsptUctum 

 times longer than broadest part; sometimes too ^^'"^^ ^"^' *^^P' 



sulc enlarged. 



small to be seen easily; often tufted at ti]) of 



stem; yellowish-green to dark green, sometimes brownish; 



silvery in B. argenteum. 



Seta %-2 inches long; reddish-brown. 



Capsule inclined, horizontal or drooping: pear-shaped or 



