216 American Midland Naturalist Monograph No. 6 



rocks, Meadow Run ravine, Sullivant Moss Society Foray. John Churchill and C. M. 

 Boardman, June 23, 1940. 



Family 31. Hypnaceae 



Autoicous or dioicous, rarely pseudautoicous or polyoicous: antheridial 

 clusters gemmiform, small, archegonial clusters on short mostly rooting peri- 

 chaetial branches: slender to robust, variously cespitose, rarely floating, dull to 

 lustrous: stem without central strand, mostly woody, often stoloniferous, mostly 

 irregularly pinnate, but the branches often regularly pinnate; leaves pluriseriate, 

 unistratose, erect-spreading to squarrose, rarely densely imbricate, often secund 

 or circinate, of various forms, sometimes unsymmetric; costa homogeneous, 

 mostly thin and rather short, simple, double, forked, or none, rarely strong 

 and complete to excurrent; leaf cells mostly narrowly prosenchymatous, rarely 

 parenchymatous, at the base looser, the alar mostly differentiated into a dis- 

 tinct group, rounded to oval or 4-6 sided, small to inflated, mostly hyaline: 

 seta elongated, mostly smooth; capsule mostly inclined to horizontal, mostly 

 arcuate, rarely pendent, or erect, mostly smooth; collum scant; peristome 

 double, both parts of same length, teeth lance- subulate, mostly strongly hygro- 

 scopic, mostly confluent at base, rarely separate, yellow, red-brown to purple, 

 mostly transversely striate with divisural zigzag, with trabeculae numerous and 

 well-developed; basal membrane of inner peristome wide, segments keeled, 

 mostly lance-subulate, cilii mostly complete, filiform, nodose to articulate, 

 rarely rudimentary or none; lid usually conic-convex, in our species obtuse to 

 acute or only very shortly rostrate; spores small. 



As here treated, a large and cosmopolitan family, distributed on all kinds 

 of substrata. The limitations of both the family and the genera are treated 

 variously by the authorities. 



Key to the Genera 



A. Costa in our species single, usually extending to leaf-middle or beyond; lid never 

 strongly rostrate; plants not complanately foliate; capsules mostly curved-cylindric, 



or subcylindric d. (Amblystegiae) 



A. Costa short, double or single or none, rarely single in Homomallium and Hygro- 



hypnum; lid sometimes rostrate B 



B. Stem-leaves and branch-leaves usually distinctly dissimilar, at least as to size, sym- 

 metric and normally inserted O 



B. Stem- and branch-leaves more or less closely similar, although often secund or 



falcate, or inserted obliquely and unsymmetricallv C 



C. Leaves either symmetric and normally inserted or unsymmetric and obliquely in- 

 serted; lid sometimes rostrate T 



C. Leaves more or less obliquely inserted and apparently two-ranked, mostly unsym- 

 metric; branches mostly complanate; lid conic to short-rostrate, rarely long- 

 rostrate u 



D. Leaves bordered 7. Sciaromium 



D. Leaves non-bordered E 



E. Leaves mostly large, broad, and obtuse or sometimes apiculate 9. Calliergon 



E. Leaves not as above F 



F. Costa strong, sub-percurrent, or sometimes excurrent C 



F. Costa not reaching leaf-apex K 



G Paraphyllia often present, polymorphic; leaves non-plicate, mostly erect-spreading; 

 more or less aquatic; basal leaf-cells mostly rectangular, mcrassate, pellucid 



