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104 BOTANICAL GAZETTE. 
Such great variations can not fail to modify plant life to a very 
great extent. The hot, scorching winds that generally accompany 
the high temperatures quickly dry up all vegetation, except along 
the water-courses. The extreme dryness of these hot winds is 
remarkable, During the great heat which prevailed in the early 
part of July, I saw the grass on the prairie, which was green aD 
fresh as prairie grass usually is, completely dried up and com 
verted into hay within a period of two hours. As a consequence 
of this dry weather, we find no annuals in summer. They ony 
appear during the spring while the ground is still moist. The 
perennials all have long root-stocks, which penetrate deeply into 
the ground and enable them to withstand the drouth effectually. 
The surface of the country west of the Red river valley is 
more rolling than in Minnesota, and is found still more so as the 
Missouri river is approached. Numerous stony knolls and long 
ranges of rocky, pointed hills mark the ancient glacial moraines: 
The flora here shows plain indications of the proximity of the 
dry, treeless plains west of the Missouri, though at the same time 
the climate is humid enough to permit species of plants to grow 
and flourish, whose principal habitat is much farther eastward. 
Here and there alkaline pools appear with their peculiar plants, 
adding largely to the variety of the flora of this region. Many 
species are found whose home in the southwest is at a high ele- 
vation, proving that as we go north the increase in latitude com- 
pensates for a decrease in elevation. 
_ A Draba, probably D. nemorosa, L. , is quite plentiful. Et 
in the spring, and flowering until late in the summer, we fi 
Vesicaria Ludoviciana, DC. Erysimum asperum, DC., var: Ar- 
kansanum, N i 
Nasturtium, near N. 
variety of this species 
