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The genus Carex in North -West America, 



By 



Theo. Holm, 



Brookland D. C. 



The present enumeration of Carices is based upon some very 

 extensive collections from Alaska, Yukon, British Columbia, Wa- 

 shington, Idaho and Oregon, made by Messrs. Wm. C. Cusick, 

 Walter H. Evans, L. F. H ender so n, C. V. Piper and Wm. 

 N. Suksdorf; the writer has, also, had access to the herbaria of 

 the Canadian Geological Survey and of the U. S. National Museum. 

 For the liberal loan of these collections and for the numerous 

 specimens, that have been kindly donated to the writer, we wish 

 to express our sincerest gratitude. 



As stated in a previously published paper, ' ) it is our Intention 

 to discuss the geographica! distribution of these species within 

 the area given, and throughout the northern hemisphere: the 

 arctic regions and the mountaineous districts farther South. While 

 thus offering these data in regard to the geographica! distribution, 

 we have thouglit that the enumeration might be of some interest 

 to students of plantgeography, as a record of all the species that 

 have been found growing within this area, from which will be seen 

 the predominance of certain ,,greges", the total absence of others, 

 and finally the association of allied types with apparently local 

 and somewhat isolated species. 



By giving an account of the association of such isolated types, 

 we hope that the establishment of these may be better understood 

 than by the diagnoses alone. For instance in regard to several 

 of the species, which have been described as new (1. c), it appears 

 as if their association with more or less related species to some 

 extent justifies our views in considering them as distinct, at least 

 so long as no intermediate forms are known to be in existence. 



1) The author: Studies in the Cyperaceae (Am. journ. of sc. Vol. XX. 

 1905. p. 301). 



Beihefte Bot. Centralbl. Bd. XXII. Abt. 11. Heft 1. 1 



