PREFACE. 



The collection of plants submitted to me for examination, though made under unfavorable 

 circumstances, is a very interesting contribution to North American botany. From the mouth of 

 the Kansas river to the "Red Buttes,'' on the North fork of the Platte, the transportation was 

 effected in carts ; but from that place to and from the mountains, the explorations were made on 

 horseback, and by such rapid movements, (which were necessary, in order to accomplish the objects 

 of the expedition, ) that but little opportunity was afforded for collecting and drying botanical speci- 

 mens. Besides, the party was in a savage and inhospitable country, sometimes annoyed by Indians, 

 and frequently in great distress from want of provisions ; from which circumstances, -and the many 

 pressing duties that constantly engaged the attention of the commander, he was not able to make so 

 large a collection as he desired. To give some general idea of the country explored by Lieutenant 

 Fremont, I recapitulate, from his repoit, a brief sketch of his route. The expedition left the mouth of 

 the Kansas on the 10th of June, 1842^ and, proceeding up that river about one hundred miles, then 

 continued its course generally along the "bottoms" of the Kansas tributaries, but sometimes passing 

 over the upper prairies. The soil of the river bottoms is always rich, and generally well timbered ; 

 though the whole region is what is called a prairie country. The upper prairies are an immense 

 deposite of sand and gravel, covered with a good, and, very generally, a rich soil. Along the road, 

 on reaching the little stream called Sandy creek, (a tributary of the Kansas,) the soil became more 

 sandy. The rock formations of this region are limestone and sandstone. The amorpha canescens 

 was the characteristic plant ; it being in many places as abundant as the grass. 



Crossing over from the waters of the Kansas, Lieutenant Fremont arrived at the Great Platte, 

 two hundred and ten miles from its junction with the Missouri. The valley of this river, from its 

 mouth to the great forks, is about four miles broad, and three hundred and fifteen miles long. It 

 is rich, well timbered, and covered with luxuriant grasses. The purple liatris scariosa, and several 

 asters, were here conspicuous features of the vegetation. I was pleased to recognise, among the 

 specimens collected near the forks, the fine large-flowered asclepias, that I described many years 

 ago in my account of James's Rocky Mountain Plants, under the name of A. speciosa, and which 

 Mr. Geyer also found in Nicollet's expedition. It seems to be the plant subsequently described and 

 figured by Sir W. Hooker, under the name of A. Douglasii. On the Lower Platte, and all the 

 way to the Sweet Water, the showy cleome integrifolia occurred in abundance. From the Forks 

 to Laramie river, a distance of about two hundred miles, the country may be called a sandy one. 

 The valley of the North fork is without timber ; but the grasses are fine, and the herbaceous plant3 

 abundant. On the return of the expedition in _ September, Lieutenant Fremont says the whole 

 country resembled a vast garden ; but the prevailing plants were two or three species of kellanthus, 

 (sunflower.) Between the main forks of the Platte, from the junction, as high up as Laramie's 

 fork, the formation consisted of marl, a soft earthy limestone, and a granite sandstone. At the 

 latter place, that singular leguminous plant, the kentrophyia montana of Nuttall was first seen, 

 and then occurred at intervals to the Sweet Water river. Following up the North fork, Lieutenant 

 Fremont arrived at the mouth of the Sweet Water river, one of the head waters of the Platte. 

 Above Laramie's fork to this place, the soil is generally sandy. The rocks consist of limestone, 

 with a variety of sandstones, (yellow, gray, and red argillaceous,) with compact gypsum or alabas- 

 ter, and fine conglomerates. 



