18 T. Holm — Studies in the Cyjperacem, 



that becomes only too evident when we remember the pre- 

 dominance of the genus in northern and colder regions. The 

 study of Carex atrata L., for instance, offers an excellent 

 example of the danger in considering specimens from a few 

 stations : the species in Colorado embraces two types and the 

 Canadian three, of which only the one, the typical atrata^ is 

 common to both regions ; of these, C. ovata Rndge seems 

 restricted to the northeastern corner of this continent. Never- 

 theless all four types have at various times been considered 

 identical. Several instances of a similar nature might easily 

 be enumerated, and it is, altogether, a most difficult task to 

 segregate or combine species in a genus as large as Carex. The 

 proposition of a few new species is the result of a careful study 

 of allies and homologues, yet the species themselves are only 

 of some interest as far as concerns their characteristics modi- 

 lied, but nevertheless referable to some allied type or types 

 with which they may have developed. 



It seems altogether as if the Rocky Mountains have been 

 the center of development of a number of types, many of which 

 are endemic, while others participated in the migration along 

 with the arctic plants towards the North wliere they became 

 distributed ; some of these have even become circumpolar.* 

 But besides these two elements of vegetation, that may be 

 considered as having originated in the Rocky Mountains tliem- 

 selves, a third one and perhaps the most interesting is com- 

 posed of arctic plants which having been forced southward 

 during the glacial epoch, remained there, making their homes 

 on the lofty mountain summits, where they are yet in exist- 

 ence. These northern and southern types are esp)ecially alpine 

 or subalpine and may, at least to some, extent, throw some 

 light upon the great problem of the origin and distribution of 

 the arctic flora. 



A. Synopsis of the Species. 



ViGNEJE 



BrachystachycB Holm. 



Carex canescens L. 39°-41° (Hall and Harbour, C. C. Parry) ; 

 Trapper's Lake (C. S. Crandall) ; common in bogs near Bob 

 Creek, La Plata Mts., alt. 10,500 ft. (Baker, Earle and Tracy); 

 Marshall Pass, alt. 10,000 ft. (C. F. Baker). 



C tenella Schk. 39°-41° (Hall and Harbour, C. C. Parry); Bob 

 Creek, La Plata Mts., alt. 10,500 ft. (Baker, Earle and'Tracy); 

 moist, shaded places in Spruce-woods on mts. near Pagosa 

 Peak, alt. 9000 ft. (C. F. Baker) ; in swamp, Graymont (C. 

 S. Crandall) ; common in swamps on Mt. Elbert, alt. 10,000 

 ft. and along Quail Creek near Steven's Mine, alt. 10,500 ft. 

 (the author). 

 * Compare : A. G. Natliorst : Polarforskningens Bidrag til Forntidens 



Vaxtgeografi (in Nordenskiolds Studier och Forskuingar. Stockholm, 1883.) 



See also : Same author in Engler'sbot. Jahrb., 1891, p. 218, etc. 



