28 Holm, The genus Carex in North -West America. 



The niimber of species of our North -West American Carices, 

 that occur in the old world, aggregates about 58, 20 of which are 

 Vigneae and 38 Carices genuinae. — 13 of these are circumpolar : 

 C. canescens, glareosa, lago^ina, incurva, ustulata, rigida, aguatüis, 

 subspathacea, rariflora, rupestris, mismidra, vaginata and pulla. 

 By comparing the Scandinavian element \ve find 44 species re- 

 presented in this region, 15 Vigneae and 29 Car. genuinae, and 

 we have only recorded the species from Arctic Scandinavia, ex- 

 ckiding the southern portions of Norway and Sweden from where 

 several of the other species are known, for instance C. tenella, 

 tenuiflora. teretiuscula etc. 



It is, on the other hand, remarkabk to note that only 

 30 species extend to Greenland, and that these are really Scan- 

 dinavian types whith the exception of: C. gi)7iocrates, pratensis, 

 festiva, stylosa and scirpoidea. Of the 27 species which our region 

 has in common with Iceland, C. festiva and scirpoidea are the 

 only ones, which are of American origin, even though they both 

 have been recorded from a few stations in Arctic Scandinavia. 

 In other words the American element which is represented in 

 Greenland, Iceland and Scandinavia is very small and none of these 

 species have found their way South to the Faeroe islands, Great 

 Britain or the Alps of Switzerland. — The number of American 

 Carices which have become distributed over the coast of Eastern 

 Asia is, also, very small, and the following species may be 

 mentioned: C. macrocepliala, Gmelini, macrochaeta, Mertensii, 

 Sitchensis, melanocarpa, scirpoidea and WiUiamsii. 



If we now examine the Care^c-vegetation of the British Isles, 

 we notice that these have 25 species in common with North- 

 West America, and 9 of these are circumpolar, but we do not 

 meet with any species here, which may be considered as American. 

 In the Alps and Pyrenees there are 27 species which, also, inhabit 

 our region, and 7 of these are circumpolar. It is an interesting 

 fact that with the only exception of C. foetida and piirenaica. all 

 the species from Great Britain and the Alps, which occur in North- 

 Wcst America, are Scandinavian, and several are arctic. 



Let US at the same time extend our comparison to the Rocky 

 Mountains of Colorado, which we have treated in a previously 

 published paper ^), From this we will see that Colorado has 63 species 

 in common with our region, 6 are circumpolar, while 21 are 

 Scandinavian. Of the 12 species which our region has in common 

 with Himalaya, C. canescens, incurva, ustulata and rigida are circum- 

 polar; the others are mostly lowland species and widely dispersed 

 throughout the northern hemisphere. 



Characteristic of the C'area?-vegetation in North-West America 

 is thus: the development of a relatively large number of types, 

 the presence of certain American species but more properly per- 

 taining to other regions of our continent, and finally the presence 

 of species known from the old world, prominent among which are 

 circumpolar, arctic and northern forms. 



ij Am. journ. ot sc. Vol. 16. 1903. p. 38. 



