Geographical Jjlstribution of the Cruciferce, 7 



Torrey and Gray are silent as to its presence on the Pacific, 

 although from Hookers work we might conclude that it existed 

 there. The E. asperum, a closely allied species, flourishes in 

 the plains eastward and westward of the mountain ranges, attain- 

 ing the latitude of 65° on the McKenzie. Strictly speaking, the 

 interior of the continent is its peculiar ground, as it does not in 

 any quarter appear to approach the sea-coast within a considera- 

 ble number of degrees. Nuttall has five others of this genus, 

 none of which have yet been noted as on British territory. One 

 i-s from Arkansas and Texas, two are from the elevated plains of the 

 Hooky Mountains, one from the banks of the Wiliamet, and the 

 fifth from the neighbourhood of Monterey, Upper California. 



The second great division of Cruciferce is like that of the Sili- 

 quosje, very extensively distributed over all the temperate climes 

 of the northern hemisphere, and British America has its portion 

 of them. In the genus Vesicaria, the V. arctica extends from 

 the island of Anticosti to the Arctic Regions, where it prevails 

 most. The borders of the eastern prairies are probably the limit 

 of its range westward, in the lat. of 52°. The V.didymoearpa is a 

 very singular species, conspicuous by its strong corymb of flowers, 

 and when in fruit remarkable for its evidently bilobed didymous 

 silicle, which is orbicular or inflated. On the Rocky Mountains, 

 from lat. 52° to 5*7°, and in all probability southwards to the 

 sources of the Platte, it seeks the deep sand-banks and sand-beds, 

 wherever its long fusiform roots may find eas}^ lodgment. 



Of all the genera of the Cruciferous order, Draba has in North 

 America the greatest number of species. Thirty belong to this 

 continent, and of those the greater part are Arctic and sub- 

 Arctic plants. Confined to high northern latitudes, and scattered 

 over the islands and shores of the Arctic Seas, we have the 

 D. algida, alpina, paucijtora, micropelala, oblongata, corym- 

 bosa, lapponica, and stellata. In the extreme north is also 

 found the D. glacialis ; but this has likewise an Alpine resi- 

 dence southwardly, on the summits of the Rocky Mountains, 

 to which the ethers apparently do not stray. The Uniba 

 Icevigata has been seen as yet only at the extremity of 

 North West America. Common to the sub-Arctic as well as 

 Arctic regions are other Drabas more likely to be fallen in with 

 by the Canadian botanist. The D. muricella exists in the 

 north, and in Labrador. The D. incana, stretching along the 

 eoast of the Frozen Sea from Unalaschka to Labrador, can be 



