THE FERN BULLETIN 



Vol. XIV. APRIL, 1906. No 2 



POLYPODIUM VULGARE ITS VARIETIES 

 IN AMERICA. 



By B. D. Gilbert. 



During the last few years I have been collecting ma- 

 terial for a monograph on Polypodium vulgare and its 

 varieties in this country. I have obtained specimens 

 from Alaska to Maine and southward, showing what in- 

 fluence climate, soil, and other environments will exercise 

 upon even such a stable plant as this. Such a collection 

 was necessary if one were to attempt to give an account 

 that should be anywhere near to a full and inclusive state- 

 ment of the forms that grow on this continent. 



But it was also evident that one must have authorities, 

 and on such a subject authorities are neither plentiful nor 

 very available. Lowe's works contain a few varieties, 

 but although the figures are fine, the names given are not 

 always trustworthy. The work that is most helpful and 

 describes the greatest number of forms is Lindley & 

 Moore's " Nature Printed Ferns." The forms there 

 illustrated are not very many, but there are seventeen 

 varieties named and described, and these cover nearly 

 all the forms known in Great Britain forty years ago. 



There was still another source of information more 

 important and necessary than the books in determining 

 the identity of specimens. Nothing can satisfactorily 

 take the place of authoritatively determined specimens 

 of the ferns themselves. This want was kindly supplied 

 by Mr. C. T. Druery of Acton, "London, England, and by 

 Dr. H. Christ of Basle, Switzerland, both of whom are 

 acknowledged authorities on ferns. Mr. Druery sent me 



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