Academy of Sciences.] CENTERS OF DISTRIBUTION. 33 



No. o.] 



Veronica alpina L. 



Widely distributed throughout the Arctic regions of Europe and Asia, the species, never- 

 theless, seems to be absent from Arctic North America, although it has been reported from 

 Greenland, Labrador, the Hudson Bay region, Alaska, and from many stations in the Rocky 

 Mountains. In Europe the species extends south to Iceland, Great Britain, and the Alps of 

 Switzerland. It is no doubt of Arctic origin, having acquired the recent wide range during the 

 glacial epoch. 



THE GENUS CASTHXEJA. 



... 



C. breviflora Gray and C. septentrionalis Lindl. are the only species which I found in the 

 Alpine region; of these the former is a native of Colorado and Wyoming, while the latter is 

 known also from Labrador, White Mountains, Alaska, Aleutian Islands, etc. It is interesting 

 to notice that C. pallida Kunth, a close ally of C. septentrionalis Lindl., is a native of the sub- 

 arctic northwest coast and islands of North America, extending from there to Arctic Asia and 

 Europe, to Greenland, and that it is known, also, from Altai and Baikal Mountains. But other- 

 wise Castilleja is best represented in the Rocky Mountains, where the genus evidently developed, 

 and from which locality C. septentrionalis Lindl., the most abundant species, became distributed 

 toward northeast and northwest, while the subarctic C. pallida Kunth even reached the Altai 

 and Baikal Mountains. 



THE GENUS PEDICULARIS. 



The species, about 120, are mainly inhabitants of mountains; several are Alpine, and not a 

 few species are known from the Arctic regions. In North America about 30 species are recorded 

 by Gray, and of these P. scopulorum Gray is a native of the Alpine regions of Colorado, some- 

 times accompanied by P. Gh'oenlandica Retz. and P. Parryi Gray which, however, are much 

 more characteristic of the spruce zone The genus is well represented in Alaska and adjacent 

 islands, several extending from there to Asia, and even to Europe. Eight of the nine species 

 known from Greenland occur also in Northeast America, Labrador, and the Hudson Bay 

 region; 22 species are recorded from the moimtains of middle Europe, several of which being 

 natives of these mountains. Of the 60 species enumerated by Ledebour (Fl. Rossica), 37 are 

 recorded from the Altai and Baikal Mountains. Four species of the genus are circumpolar, 

 P. lapponica L., P. sudetica Willd., P. Mrsuta L., and P. lanaia (Willd.) Cham., and these may 

 have originated in the Arctic mountains. The other species may have developed from several 

 centers south of the boreal regions, and very remote from each other, viz, the mountains of 

 middle Europe, Altai and Baikal Mountains, Rocky Mountains, and partly, also, the Caucasus. 



POLYGONUM BISTORTOIDES Pursh. 



By Meisner 37 this plant is considered to be identical with P. Bistorta L., a view held by 

 several other authors, and Macoun (1. c.) enumerates P. Bistorta L. as the species of Arctic 

 America, with P. bistortoides Pursh as a mere synonym. Whatever importance be attached to 

 the difference in leaf outline, the plant of the Rocky Mountains does appear somewhat distinct 

 from typical P. Bistorta L., and may deserve, at least, rank as variety. In considering the 

 geographical distribution of both, we notice that P. Bistorta L. is widely distributed through the 

 northern and Arctic regions of Russia and Siberia, extending south to the mountains of middle 

 Europe, to the Caucasus, Baikal and Altai Mountains, while the so-called P. bistortoides Pursh 

 is a native of the mountains of Montana, Washington, Colorado, New Mexico, and California. 

 According to Ledebour (1. c.) P. Bistorta L. is, in Altai and Davuria, accompanied by two vari- 

 eties: "foliis latioribus," and "foliis angustioribus ;" of these the latter maybe identical with 

 the Rocky Mountain plant, but I have seen no specimens of the Asiatic, except from the Arctic 

 regions. 



37 Monographiae generis Polygoui prodromus. Geneva, 1826. 



