362 AKNUAL REPORT. 



ent. The summer is very dry; showers are of rare occurrence ; and 

 the temperature varies excessively. Thus in the month of July the 

 mercury rose to 115° Fahrenheit, and fell to 32°. 8uch great 

 variations cannot 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 and fresh as prairie 

 grass usually is, completely dried up and converted into hay within 

 a period of two hours. As a consequence of this dry weather, we 

 find no annuals in summer. They only 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 Mis- 

 souri 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, tree- 

 less plains west of the Missouri; though at the same time the cli- 

 mate 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 elevation, 

 proving that as we go north the increase in latitude compensates 

 for a decrease in elevation. 



Scattered over the drift hills in great abundance, and the first 

 flower to appear in spring is Anemone patens, L., var. Nuttcdiana^ 

 Gray, attaining a luxuriance of growth never met with in Minne- 

 sota. After crossing the Missouri and the western boundary of the 

 glacial drift, this plant wholly disappears. In the moist places of 

 the prairies is found Ranunculus glaherrimiis^ Hook., and around 

 alkaline ponds R. Cymhalaria, Pursh, the latter being very abun- 

 dant west of the Missouri river. Another representative of this 

 genus resembles R. rliomboldeus, Goldie, but differs from that in its 

 more erect and taller growth and much smaller flowers. It appears 

 to be some undescribed species. 



A Draba, probably D. nemorosa, L., is quite plentiful. Earlj'- in 

 the spring, and flowering until late in the summer, we find Vesi- 

 caria Ludoviciana, DC. Erysimum asperum. DC, var. Arkansanum^ 



