199 



Lamina stalk 2-8 cm. long (Northern States). 



9. B. Matricariae (Schrank) Spreng. 

 Segments mostly rounded apically, cuneiform to lunulate (Southern States 

 and Jamaica). 

 Spores maturing from February to April. 



Bud with a few scattered hairs, lamina sessile or nearly so, seg- 

 ments mostly fan-shaped (Southern States). 



10. B. biternalum (Lam.) Underw. 

 Bud densely hairy, lamina stalked, segments mostly oval or ovate 

 (Jamaica), li. B. JenmaniUndtrwoodi. 



Spores maturing from July to October. 



Plants slender, lax, segments cuneiform to lunulate (Southern 

 States). 12. B. alabamense Maxon. 



Plants rather stout, segments spatulate to ovate (Jamaica). 



13. B. Underwoodianum Maxon. 



Form differentiation in the group seems to correspond in most 

 cases to the broader differences in chmatic conditions as is indi- 

 cated by the distribution accredited to some of the associated 

 species. This differentiation, however, has apparently not pro- 

 ceeded exactly the same in different groups. B. obliqiium, as 

 recognized here, includes both the northern B. obliqimm (in a 

 more limited sense), the southern B. tejtziifolmm, and a Jamaican 

 plant. The first two comprise extremes differing sharply from each 

 other,* but which appear to be connected by all manner of inter- 

 mediates in form and distribution. For the Jamaican plant I 

 have been able to find no constant differences other than size. 



In the B. silaifoliinn line on the other hand, not only are the 

 extremes in form distinctly marked, but there seems to be a dis- 

 continuity in distribution as well, and no real intermediates are 

 known. The line includes six forms in the eastern region. In 

 the north are B. silaifolmni {B. obliquum v. iittermedhiin of 

 authors), and B. Matricariae , the latter perhaps only a local 

 alpine adaptation. In the Southern States we have B. biternatimi 

 and B. alabamense, differing both in form and in time of fruiting, 

 and in Jamaica the parallel pair B. Jenmani and B. Underwood- 

 ianum. Further collections, for example in Cuba, may compli- 

 cate the synopsis of these plants, but at present they seem very 

 deservedly distinct. 



* B. obliquum: segments somewhat contracted, the margins revolute, obscurely 

 crenulate. 



B. tenuifoliam Underwood : segments expanded, thin, the margins plane, sharply 

 serrulate or denticulate. 



