Arctic Plants: Geographical Distribution 



97 B 



North America, of which 3 inhabit the Coast range, 1 tjie Cascade mountains, 

 6 the Rocky mountains,. and 8 the Appalachian mountains; finally, of our 19 

 species of Alsine, 2 occur in the Coast range, 3 in the Cascade mountains, 5 in 

 the Rocky mountains, and 4 in the Appalachian mountains. 



The general distribution of the number of species may be seen from the 

 accompanying table (Table 3). Considering the fact that the column "Moun- 

 tains of North America" comprises the Coast range, the Cascade mountains, 

 the Rocky mountains, and the Appalachian mountains, the number of species is 

 remarkably small as compared with Altai, and especially with Caucasus, so far 

 as concerns Silene and Cerastium especially. The number of species from the 

 Alps and Pyrenees is also small as compared with Altai and Caucasus. With 

 regard to the number of species endemic to Caucasus, there are 15 species of 

 SUene, 9 of Cerastium,i7 of Alsine, and 2 of Stellaria; endemic to Altai are 4 

 species of Stellaria, 2 of Cerastium, and 1 of Lychnis. 



And as may be seen from the same table (Table 3), the contingent of these 

 mountains to the arctic Flora is very small; still, as has been mentioned above, 

 the CaryophyUaceae are quite frequently met with in the arctic region, and six 

 of those collected by the expedition are even circumpolar and extend very far 

 north. It would thus appear as if these circumpolar species besides Stellaria 

 longipes originated in the arctic regions, where they are better represented than 

 anywhere else farther south. However, Halianthus, although being circumpolar, 

 must not be included, since it is a lowland plant inhabiting the seashore farther 

 south; the migration of this plant to the polar regions must undoubtedly have 

 taken place at the same time as so many of the other southern species accom- 

 panied the arctic on their retreat to the north. 



Merckia physodes is undoubtedly a genuine arctic type, known only, so far, 

 from Alaska, Eschscholtz bay and Norton bay to Point Barrow, Mackenzie 

 delta, and northeastern Siberia, Konyam bay, and mouth of the river Kolyma. 

 Alsine arctica and A. macrocarpa are both recorded from the north coast of 

 Siberia by Ledebour and Kjellman, and the former has also been collected in 

 the Altai mountains and in Kamtchatka. 



Very remarkable is the distribution of Cerastium maximum L. (C. grande 

 Greene). This species has been reported from arctic Siberia: Mouth of the 

 river Kolyma (Angustinowicz), and Pitlekaj (Kjellman); furthermore, from 

 several stations in the Altai and Baikal mountains, from the arctic coast of this 

 continent, from Yukon (Hunker creek), and finally from as far south as Caucasus. 



24657—7 



