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Rydberg's Flora will well satisfy a botanical need that has 

 become more acute in recent years with the rapid development 

 of the montane states. Only those who have occasion to de- 

 termine large collections of plants from this region, especially 

 the marginal portions, where nomenclature and taxonomy have 

 been a matter of accident rather than science, can fully appreciate 

 its value. The Rocky Mountain area is a striking example of 

 insularity in botanical work. Too often isolated individuals, 

 actuated by the best of motives, but frequently without the 

 assistance of adequate literature or herbaria, have carried for- 

 ward their work independently of that done in other centers. 

 Unwarranted importance has been assigned to geographic iso- 

 lation as a factor in determining specific distribution, with the 

 result that a given species has sometimes been described several 

 times from separated localities. If this Flora were no more than 

 a correlation of nomenclature it would still serve an invaluable 

 purpose; but it is far more than a "nomenclator." 



No botanist is so well qualified as Dr. Rydberg to prepare a 

 manual of the Rocky Mountains. For twenty-five years the 

 flora of this vast and varied region has been almost the sole 

 subject of his study in herbarium and field. Although most of 

 the work has been carried on at the New York Botanical Garden, 

 all the larger herbaria and some of the smaller ones have been 

 visited, and the author has obtained a field acquaintance with 

 the plants through several seasons' botanizing in the most in- 

 teresting regions. He has already published, besides numerous 

 short systematic papers and a series dealing with phytogeography, 

 two important works on Rocky Mountain botany, the Flora of 

 Montana and the Yellowstone National Park (1900) and the 

 Flora of Colorado (1906). The intimacy of his association with 

 Rocky Mountain plants is indicated by the fact that in the present 

 book almost a thousand species bear his name as author. 



This latest manual is the first to give an adequate idea of the 

 richness of the mountain flora. The species described number 

 5,897, distributed among 1,038 genera. The largest family, of 

 course, is the Asteraceae, comprising 1,068 species, giving, with 

 the Cichoriaceae and Ambrosiaccae, a total of 1,224 species of 



