262 A MANUAL OF MOSSES 



la. Elodium paludosum variety elodioides (Renauld and Car- 

 dot) Best. 

 (Thtiidiwu elodioides Renauld and Cardot). 



Leaves smaller with margins dentate-serrate, the cells 

 more or less strongly and often sub-centrally papillose; darker 

 green; cells shorter, elliptic or oval. 



In swampy meadows, swamps, bogs, etc.; from New York 

 to Ohio and Indiana. Apparently rare in our region. 



McKean : D. A. Burnett. Bradford. 



Family XXXI. HYPNACEAE. 



Autoicous or dioicous, rarely pseudautoicous or poJyoi- 

 cous : antheridial clusters gemmdform, small, archegonial .clus- 

 ters on short mostly rooting perichjetial 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-spreadii^ to 

 squarrose, rarely densely imbricate, often secuud 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 nar- 

 rowly prosenchymatous, rarely parencliymatous, at the base 

 looser, the alar mostly differentiated into a distinct group,- 

 1 ounded 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 hygroscopic, 

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

 purple, mostly transversely striate, with divisural zigzag, with 

 trabeculse numerous and well-developed; basal membrane of 

 inner peristome wide, segments keeled, mostly lance-subulate, 

 cilia mostly complete, filiform, nodose to articulate, rarely rudi- 

 mentary or none; lid usually conic-convex, in our species ob- 

 tuse to acute or shortly rostrate ; spores small. 



A large and cosmopolitan family of Z7 genera, distributed 

 on all kinds of substrata. 



Key to the Genera. 



a. Costa in our species single, extending to leaf-middle or beyond; 



lid never rostrate. d. (Amblystegieae) . 



a. Costa short and double or none; lid sometimes rostrate. 



b. 

 b. Stem-leaves and branch-leaves usually distinctly dissimilar, 



symmetric and normally inserted. o. (Hylocomieae). 



b. Stem- and branch-leaves more or less closely similar, often 

 inserted obliquely and unsymmetrically. c. 



