Arctic Plants: Geographical Distribution 127 -b 



Concerning the material collected, Aster sibiricus is the only member of the 

 genus represented; it is not confined to the arctic coast, however, and occurs 

 also in Alaska with adjacent islands, besides in the Rocky mountains of Wyoming 

 and Montana; it is not arctic in Siberia, but is reported by Ledebour from Altai, 

 Baikal, andDavuria. Aster alpinus L. and A. pygmaeus Lindl. have both been 

 collected in the arctic regions of this continent to which the latter is confined; 

 the former occiirs also in the Rocky mountains down to about Lat. 49° (Drum- 

 mond) and is, furthermore, indigenous to Central Russia, Caucasus, Altai, 

 Baikal, and Davuria. Aster Tripolium L. grows in Finmark, mostly represented 

 by the variety arcticus Th. Fr. 



In Erigeron we have the circumpolar E. uniflorus, also widely distributed 

 in the south, frequently accompanied by E. alpinus. E. grandiflorus, and E. 

 compositus, on the other hand, are better represented in the Rocky mountains 

 where they evidently developed. As a matter of fact these mountains, rich as 

 they are in species of the genus, constitute one of the most important centres; 

 only seven species have been reported from Caucasus two of which are endemic, 

 and the same figures may also be applied to Altai. 



The circumpolar Antennaria alpina may well be considered as one of the 

 parental types from which the North American element has developed. It is 

 interesting to notice the abundance of species of the genus which are represented on 

 this continent, even though much too many have been proposed, in comparison 

 with the representation of the genus in the Old World: A. alpina (L.)' R. Br., 

 A. carpathica R. Br., A. dioica Gaertn., A. rubicunda Koch (Armenia), and A. 

 Steetziana Turcz. (Baikal, Davuria) ; however, the last of these is by Trautvetter 

 (Increm. p. 412) considered identical with Leontopodium sibiricum. 



Chrysanthemum integrifolium and C. arcticum are the only species of the 

 genus 'indigenous to North America; of tJiese the former is confined to the arctic 

 sea coast and "Terra Tschuktchorum" while the latter extends from Hudson 

 bay to arctic Alaska, Kamtchatka, eastern Siberia (Pitlekaj Long. 173° 24' W.); 

 it has also been found in Lapland. 



While the genus Pyrethrum, a near ally of Chrysanthemum, on this continent 

 is only represented by a single species, the arctic bipinnatum Willd., it is in Siberia 

 and Russia exemplified by about 40 species, mostly natives of Altai and Caucasus. 



About 120 species of Artemisia are recorded from Russia and Siberia by 

 Ledebour and Trautvetter, and about 60 from this continent; most of these are 

 lowland plants but some have also been recorded from the mountains, notably 

 from Caucasus (about 20 species), Altai (about 40 species), and the Rocky 

 mountains (about 15 species). 



Some of the American element is best represented in the arctic regions, for 

 instance: A. 'Richardsoniana, A. senjavinensis Bess., A. glomerata Ledeb., A. 

 globularia Cham., and A. borealis Pall., where they evidently developed, and 

 these regions may thus have constituted an important centre for several of the 

 alpine species farther south; some other centres, and perhaps still more important 

 to the development of species, may have been situated in Caucasus and Altai. 



The large genus Senecio is also well represented in Eurasia and North America 

 but very few occur in the arctic region; these are mainly the same species and 

 they are almost circumpolar. 



Crepis nana Richards, is by Ledebour referred to the genus Youngia and it 

 is the only one known from this continent, being distributed from the arctic 

 coast and islands south along the mountains to Colorado and California; in Asia 

 the species has been reported from Altai, Baikal, and Davuria. Some other 

 species of Youngia are described by Ledebour, one from Caucasus, and 3 from 

 Altai, Baikal, and Davuria. It would thus appear as if this singular little genus 



