64 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



CONTRIBUTIONS TO THE FLORA OF IOWA.— 



No. VI. 



BY J. C. ARTHUR. 



Presented before the Diivcnport Academy of Sciences, February Sth, 1S84. 



Only phanerogams have been inckided, heretofore, in the present 

 series of contributions. In this number an innovation is begun by ex- 

 tending the catalogue to the pteridophytes, which is to be continued, 

 in succeeding numbers, until all the orders of lower plants, in their 

 proper sequence, are eventually included. A large amount of material 

 for this purpose is already on hand. The manner of cataloguing will 

 be essentially the same as observed in the phanerogamic portion, and 

 the whole is intended to finally present a uniform list of the Iowa flora. 

 The numbers are continued from the catalogue of 1876 (Contr. No. I.). 

 Their value lies in securing greater ease of reference, and in permitting 

 subsequent discoveries to be readily referred to their approximate 

 places in the list ; for, on account of the numerous interpolations, they 

 no longer serve to show the total number of species recorded. 



The practice in the phanerogamic portion has been to use the nomen- 

 clature that accords with the latest information, but to adhere to the 

 sequence of orders given in Gray's Manual, 5th edition. Subsequent 

 changes of synonymy, or of previous changes not known to the writer 

 at the time of publication, have not been recorded. On the other hand, 

 all errors of determination have been corrected in the contribution fol- 

 lowing their discovery. This leaves the catalogue as accurate as pos- 

 sible in regard to the primary fact of the occurrence of the species 

 within the State, but in some instances quite out of date in regard to 

 synonymy and distribution. These defects can be remedied at some 

 future time by revising the whole list, bringing the synonymy up to 

 date, and adding the localities reported since the first }niblication. 



In enlarging the scope of the catalogue, it becomes necessary to 

 adopt some system of classification for the added portion. Whatever 

 system is used, it is desirable that it be familiar to the several collect- 

 ors of the State and others assisting in the work, or one easily obtained 

 by them. That given in Bessey's "Botany for High Schools and Col- 

 leges" has, therefore, been adopted for the sequence of the orders, as 



