Oct. 



1^771 



NA TURF. 



539 



J. D. Hooker has already accomplished, and by which his 

 high scientific position has been earned, must needs be 

 either too technical or too long for a sketch like this. 

 Moreover, the Atlantic is no longer what it once was, when 

 a judgment wafted across it either way was invested with 

 somewhat of the character of the verdict of posterity. And 

 the close relations for forty years of the present writer 

 with the Hookers, father and son, disqualify him for the 

 office of judge. Let that duty devolve upon our suc- 

 cessors. 



The knowledge and experience of most of our eminent 

 botanists have been gained, and their work mainly done, 

 in the herbarium and botanic garden. No living botanist 

 that we know of has shared Sir J. D.Hooker's opportunities 

 of studying in place the living vegetation of so many parts 

 of the world; these include, besides those already men- 

 tioned as places visited during his Antarctic voyage, the 

 southern shores of Europe, North Africa, Palestine, and 

 India to the Chinese borders. When we have welcomed 

 him to New England, as we hope to do before these lines 

 are in print, and when he has traversed our continent 

 from the Atlantic to the Pacific, it may confidently be 

 affirmed that he has seen far more fioTavrj than ever fell to 

 the lot of any other of his craft. 



Sir J. D. Hooker was elected President of the Royal 

 Society in 1S73, an office which he still holds. 



May, 1S77 Asa Gray 



NOTES ON THE BOTANY OF THE ROCKY 



MOUNTAINS 

 [The contemplated visit to the United States of America 

 alluded to in the preceding article has now been accom- 

 plished, and Sir Joseph Hooker has favoured us with the 

 notes of his journey following.] 



IN company w ith Dr. Asa Gray, Professor of Botany of 

 Harvard University, Cambridge, U.S., I availed myself 

 of an oft-repeated invitation to us both from Dr. Hayden, 

 the distinguished chief of the Topographical and Geo- 

 logical Survey of the United States Territories, to join 

 the Survey in Colorado and Utah ; this we did with the 

 view cf instituting a comparison between the floras of 

 these central and elevated territories and those of other 

 parts of the continent, and thus obtaining some insight 

 into the origin and distribution of the North American 

 flora. In order to comprehend the importance of Colo- 

 rado and Utah as the basis for such investigations, I 

 should state that they occupy a very central position in 

 the continent, and include a section of the Rocky Moun- 

 tains about 300 miles long and about as broad, namely, 

 from N. lat. 37' to 41^, and from W. long. 105° to 112*'. 



The mountain region thus limited consists of exten- 

 sive and often level floored valleys, sometimes many miles 

 broad, and elevated 4,000 to 5,000 feet above the sea, 

 called " parks " in local topography, which are interposed 

 between innumerable rocky mountain ridges of very 

 various geological age and formation, which often reach 

 12,000 feet, and sometimes 14,000 feet elevation, the 

 maximum being under 14,500. 



Those of the so-called parks which are watered by 

 rivers that flow to the east are continuous with the 

 prairies that lie along the eastern flanks of the Rocky 

 Mountains ; those watered by rivers that flow to the west 



are continuous with the so-called desert or salt regions 

 that lie along the western flanks of the range ; but the 

 divides between the head waters of the streams that flow 

 either way are often low, and the botanical features of the 

 east and west may hence meet and mix in one park. 



Such a section of the Rocky Mountains must hence 

 contain representatives of three very distinct American 

 floras, each characteristic of immense areas of the con- 

 tinent. There are two temperate and two cold or mountain 

 floras, VIZ. : (i) a prairie flora derived from the eastward ; 

 (2) a so-called desert and saline flora derived from the 

 west ; (3) a sub-alpine ; and (4) an alpine flora ; the two 

 latter of widely different origin, and in one sense proper 

 to the Rocky Mountain ranges. 



The principal American regions with which the com- 

 parison will have first to be instituted are four. Two of 

 these are in a broad sense humid ; one, that of the 

 Atlantic coast, and which extends thence west to the 

 Mississippi river, including the forested shores of that 

 river's western affluents ; the other that of the Pacific 

 side, from the Sierra Nevada to the western ocean : and 

 two inland, that of the northern part of the continent 

 extending to the Polar regions, and that of the southern 

 part extending through New Mexico to the Cordillera. 

 of Mexico proper. 



The first and second (Atlantic plus Mississippi and the 

 Pacific) regions are traversed by meridional chains of 

 mountains approximately parallel to the Rocky Moun- 

 tains ; ramely, on the Atlantic side by the various systems 

 often included under the general term Appalachian, which 

 extend from Maine to Georgia, and on the Pacific side by 

 the Sierra Nevada, which bounds California on the east. 

 The third and ''ourth of the regions present a continuation 

 of the Rocky Mojntains of Colorado and Utah, flanked 

 for a certain distance by an eastern prairie flora extend- 

 ing from the British possessions to Texas, and a western 

 desert or saline flora, extending from the Snake River to 

 Arizona and Mexico. Thus the Colorado and Utah 

 floras might be expected to contain representatives of all 

 the various vegetations of North America except the small 

 tropical region of Florida, which is confined to the 

 extreme south-east of the Continent. 



The most singular botanical feature of North America 

 is unc[uestionably the marked contrast between its two 

 humid floras, namely, those of the Atlantic plus Missis- 

 sippi, and the Pacific one ; this has been ably illustrated 

 and discussed by Dr. Gray in various communications to 

 the American Academy of Sciences, and elsewhere, and 

 he has further largely traced the peculiarities of each to 

 their source, thus laying the foundations for all future 

 researches into the botanical geography of North 

 America ; but the relations of the dry intermediate re- 

 gion either to these or to the floras of other countries 

 had not been similarly treated, and this we hope that we 

 have now materials for discussing. 



Our course and direction in America was directly 

 westward to Colorado, where we followed the eastera 

 flanks of the Rocky Mountains for about 300 miles, that 

 is from Denver in the north, to near the borders of New 

 Mexico, ascending the highest northern and southern 

 peaks, and visiting sevend intermediate parks and valleys, 

 watered by tributaries of the Arkansas, Platte, Colorado, 

 and Rio Grande. From Denver we proceeded north 



