HYPNACEAE 231 



Ptilium crista-castrensis (L.) De Not. (Ilypnum 

 crista-castrensis L.) is readily distinguished by its 

 plume-like character, due to the regularly and closely 

 pinnate branching extending to the tip of the stem, and 

 the strongly curved and crowded leaves. The plants are 

 often found mixed with other mosses, but are always 

 striking and conspicuous. The poorer growth may 

 somewhat resemble Stereodon imponens (p. 233). 

 Stereodon usually grows more prostrate, and the 

 branches are shorter, more irregularly and unequally 

 pinnate. See Stereodon curvif alius (p. 234). 



71. STEREODON (Brid.) Mitt. (Ste-re-o-don) 



A very large genus, confined chiefly to temperate 

 regions; a few species occurring commonly in our range. 

 Name derived from the Greek for '' firm " or '' stiff,'* 

 and " tooth," referring to the structure of the peris- 

 tome. 



a. Leaves curved, spreading, in most species turned in 

 two opposite directions, and apparently in two rows, 

 giving a flattened, braided appearance along the stem 

 and branches, turned in one direction in 5. arcuatus; 

 usually large enough to be seen .... 



S. rcptilis. S. cnpressiformis. 



S. imponens. S. recurvans. 



S. curvifolius. S. arcuatus. 

 h. Leaves straight, erect, arranged equally around stem 

 and branches, easily seen .... 5*. Haldanianus. 



