102 



ably impossible to draw up a synopsis or descriptions which will 

 differentiate the very young and immature forms of B. simplex 

 from similar forms of B. tencbrosum and B. viatricariaefoliiini 

 and perhaps others. The identity of such forms can usually be 

 ascertained from the mature plants associated with them. As 

 regards the most closely related units, these are in each case keyed 

 out in pairs, so that doubtful specimens may be traced at least to 

 one of two. 



Commonstalk about one-half hypogean, the lamina straight in vernation, entire to 

 once or twice pinnately or sometimes subternately divided into cuneiform to lunu- 

 late, usually separated segments ; the sporophyl straight in vernation, long-stalked, 

 often one-half to two-thirds the height of the plant (in meadows and pastures, 

 northern North America, Europe, and Asia). i. B. simplex Hitchcock. 



Commonstalk all or nearly all hypogean, lamina with the tip bent down in vernation, 

 once ternately divided, the divisions pinnately divided into cuneiform to lunulate, 

 crowded segments ; the sporophyl erect in vernation, short-stalked, scarcely ex- 

 ceeding the lamina (in pumice soil, 9000 ft. elevation, Oregon). 



2. B. pumicolaCo\i\\e. 

 Commonstalk nearly all epigean. 



Lamina oblong to ovate or narrowly deltoid, with only the tip or upper part bent 

 down in vernation ; the sporophyl erect or with the tip bent down. 

 Lamina with the tip bent down in vernation, but not clasping the sporophyl, 

 ovate to deltoid, acutish, sessile, usually only once pinnately divided, the 

 segments rhombic to deltoid, acutish (Alaska, also in Europe). 



/ 3. B. boreale Milde. 



Lamina with the tip bent down in vernation and clasping the sporophyl, 

 oblong, rounded, usually sessile or nearly so, only once pinnately 

 divided with fan-shaped to lunulate segments. 

 Plants usually slender, lamina narrowly oblong, the segments fan- 

 shaped, distant (central New York, northern Michigan, and Mon- 

 tana). 4. B. onondagense Underwood. 

 Plants usually stout, lamina usually broader, the segments lunulate, 

 often close and imbricate (northern North America and Europe). 



5. B. Lunaria (L. ) Sw. 

 Lamina with the tip or upper part bent down in vernation and clasping the 

 sporophyl, oblong to ovate or sometimes deltoid, usually stalked, 

 entire to twice pinnately divided with cuneiform, oblong, or ovate 

 segments. 

 Segments mostly cuneiform; sporophyl erect in vernation (in wet 

 woods, northeastern states and Canada). 



6. B. tenebrosum A. A. Eaton. 

 Segments mostly oblong or ovate, the sporophyl with the tip bent down 

 in vernation (usually in dry ground at the edge of woods and 

 thickets, northern North America and Europe). 



7. B. neglectutn Wood. 



