44 T. Holm. — Studies in the Cyperacem* 



tinent are some alpine species : C. elynoides^ Engehnanni, 

 chcdciolepis, chimaphila, scojndormn and hella. We have 

 already discussed the distribution of C. chalciolepis and hella^ 

 both of which show affinities to C. atrata. In regard to C. 

 scopidorum this is undoubtedly a southern type, but has, how- 

 ever, spread farther ]^orth to Wyoming and Montana, but is not 

 reported as being frequent. C. elynoides is hardly to be con- 

 sidered as a rare species, since its great resemblance to Elyna 

 spicata may have caused it to be confounded with this, besides 

 that relatively few species of Carex are represented in the 

 herbaria from the higher alpine regions of these mountains. 



There is thus quite a number of Caricesin Colorado endemic 

 to this country, and although these are not of so much interest 

 from a geographical viewpoint as the northern, common to 

 both worlds, they will, no doubt, prove valuable to the study of 

 homologues, such as many of these actually are, of old world 

 species. 



Considering the arctic species, which are, also, occurring in 

 Colorado, we have demonstrated the possibility of some of these 

 having originated in the arctic region: C. incurva, rigida^ 

 rupestris^ miscmdra, pidla, nardina and riiicroglocliin. Not 

 less than five of these are, also, circumpolar and it seems as if 

 the existence of these, together with C. nardina and micro- 

 glochin^ indicate that the Rocky Mountains harbor a certain ele- 

 ment of that flora, which we call the arctic, which was reared 

 in the polar-regions, but forced south during one of the greatest 

 revolutions in the history of the earth, known as the glacial 

 epoch. Some of the other Carioes which we have enume- 

 rated from Colorado are, also, arctic, but neither circumpolar or 

 having originated in the extreme North, as far as we know, 

 for instance C. atrata, alpina^f estiva, schpoidea and gy no- 

 crates, and these illustrate a flora partly of American, partly also 

 of old world origin. Most of the others are truly American 

 types, and evidently young types. 



If it had been within the scope of the present paper to con- 

 sider other genera than Carex, as represented in Colorado and in 

 the arctic region, we would have been able to offer further evi- 

 dence of the existence of a glacial flora in the Rocky Mountains, 

 easily illustrated by a number of other types, such as Dryas 

 octopetala, Silene acaulis, Camjxmiila uniflora, Saxifraga 

 nivalis, cerniia and flagellaris, Lloydia serotina and many 

 others. But when we undertook the task of discussing the geo- 

 graphical distribution of the genus Carex in Colorado and quite 

 especially that of the alpine types, it was simply the writer's 

 intention to make an attempt to show, that even a single genus 

 of 23lants might offer some tangible proof of the foundation of the 

 theory relating to the history of arctic plants, as demonstrated 

 in the writinofs of the Swedish naturalist A. Gr. Nathorst. 



Brookland, D. C, December, 1902. 



