T. Holm — Studies in the Cyperacece. 41 



of the distribution of this species, C. f estiva, its geographical 

 center and, also, its center of development seems to have been 

 in the South, in the Rockj Mountains, where it is, thus, typi- 

 cally developed, accompanied by allies and most abundant. 

 And its occurrence in the arctic region may be explained in 

 this way, that individuals of this species were among those that 

 migrated northward with the arctic plants. This instance of 

 an arctic plant having evidently originated in the South may 

 easily be supplemented with others, and there is even among 

 the circumpolar Carices from Colorado a species which seems 

 to illustrate the same case : C. eanescens. This species is also 

 rather rare in the extreme North, while it abounds farther 

 South, associated with more or less deviating forms, besides by 

 close allies. Moreover this species is especially frequent in the 

 lowlands of J^orth and Middle Europe, Central Asia and of the 

 temperate zones of this continent, extending throughout the 

 southern portions of South America to Tierra del Fuego. But 

 it is, of course, impossible to define the original center of a 

 species with such wide distribution as C. eanescens, with any 

 closer proximity than that the center was evidently in the tem- 

 perate zone. The remarkable predominance of varieties of G. 

 eanescens on this continent in contrast to Europe and Asia, 

 might point towards its center as being looked for here, inas- 

 much as it is here surrounded by such species which we, for 

 morphological reasons, consider as close allies, e. g., C. vitilis, 

 trisperma, tenuiflora, loliacea and tenella, of which only the 

 first, 0. vitilis, has reached beyond the arctic circle. 



These examples might be sufiicient for illustrating the prob- 

 able southern origin of certain plants that are, also, known as 

 "arctic." But in regard to the other circumpolar Carices 

 from Colorado, we are unable to locate the original center of 

 these but in the polar regions. C. rigida, w.isandva Sindpulla 

 appear as a matter of fact not only to have their greatest distri- 

 bution within these regions, but they exhibit, besides, a much 

 more pronounced tendency to develop varieties than they do 

 farther south, where they are relatively very rare. The mono- 

 and homo-stachyous C. rupestris and incurva lack the plasticity 

 of the hetero-stachyous species and occur only as typically 

 developed, wherever they are found ; but their prevalence in 

 the ]^orth make us suppose that they originated there. We 

 may for similar reasons attribute a northern and arctic center 

 of distribution to C. nardina and C. microglochin. But in 

 regard to the other members of the category, "Arctic, but 

 not circumpolar types," w^e believe that all of these came from 

 stations south of the arctic region. Let us, for instance, con- 

 sider C. atrata and aljnna. The former is only known as 

 arctic in a few stations of the European continent, while the 

 other has been collected in arctic Eussia, Finmark, Greenland 



