I From the 1'iii.letin of the Tohkry Hoianicat. Chip, 37: 313-335. 1910.] 



Studies on the Rocky Mountain flora — XXII 



Per Axel Rydberg 



Erigeron 



Just as the writer resumed his work on Erigeron, Coulter and 

 Nelson's New Manual of Botany of the Central Rocky Mountains 

 came out. From all evidences it is apparent that most of the 

 work in connection with the new book has been done by Professor 

 Aven Nelson, of the University of Wyoming. The work is a 

 great improvement on the old Coulter's Manual and it is perhaps 

 the best manual that has been put out treating on the botany of 

 the West. It has, however, many features to which the present 

 writer is unwilling to subscribe. Dr. B. L. Robinson in his recent 

 review* has pointed out the unevenness in the nomenclature, in 

 that the Vienna Code has been followed in some cases, in other 

 cases not. But this is easy for me to understand, for Professor 

 Nelson has until lately followed the "Rochester Code," and it is 

 not so easy to change the nomenclature of one's thinking and 

 writing and make it self-consistent. 



A few years ago, when Professor Nelson published his "New 

 Plants from Wyoming" in the Bulletin of the Torrey Botanical 

 Club, he was about as "radical" as the present writer, and had 

 about the same limitation of species. If we should judge from the 

 New Manual, his conception of a species seems to have changed 

 considerably, as seen from the number of specific names reduced 

 to synonymy. Whether this change of attitude has slowly grown 

 upon Professor Nelson or is due to influence from his collaborators, 

 I can not tell. There is, however, one feature in this connection 

 that seems to me somewhat unexplainable. Professor Cockerell 

 in his review t of the book stated: 



"I have had the curiosity to count the number of species 

 admitted as valid in the new manual, which were undescribed 

 at the time of the publication of the first edition in 1885. They 



*Rhodora 12: 13-16. Ja 1910. 

 fScience II. 31: 302. 1910. 



313 



