ASA GRAY. 337 



work on a second edition of the " Manual," partly in response to a re- 

 quest from Darwin for a list of American alpine plants. In this paper 

 he gave a general view of the characteristics of the North American 

 flora, with tahles of species showing the extension of alpine plants, and 

 the comparative distribution of Eastern and Western species, and their 

 relation to species of Europe and Asia, although he states that he must 

 defer making an extended comparison with the plants of Northeastern 

 Asia until he has studied some recent collections from the northern 

 part of Japan. The most important conclusions reached in this paper 

 may be stated in his own words: "All our strictly subalpiue species 

 (with two exceptions) which are common to us and to Europe, extend 

 northward along the central region of the continent quite to the arctic 

 sea-coast. While curiously enough, eleven, or one third of our strictly 

 alpine species common to Europe, — all but one of them arctic in the 

 Old World, — are not known to cross the arctic circle on this conti- 

 nent. This, however, might perhaps have been expected, as it seems 

 almost certain that the interchange of alpine species between us 

 and Europe must have taken place in the direction of Newfoundland, 

 Labrador, and Greenland, rather than through the polar regions." 

 Again : " The special resemblance of our flora to that of Europe, 

 it is clear, is not owing simply either to the large proportion of genera 

 in common, or to anything striking or important in the few genera 

 nearly or quite peculiar to the two. The latter, indeed, are insignifi- 

 cant in our flora, and not to be compared, as to any features they 

 impart, with the much more numerous and really characteristic genera 

 which are shared by the Eastern United States and Eastern temperate 

 Asia. We must look for it in the species, partly in the identical ones, 

 and partly in those which closely answer to each other in the two floras." 

 He accounts for such cases as the occurrence of Phryma Leptostachya 

 in the United States and Nepal as follows : " We should therefore look 

 in one and the same direction for the explanation of these extraordinary 

 no less than of the more ordinary cases of distribution, and . . . should 

 refer such anomalous distribution to very ancient dispersion." 



The plants from Japan to which he referred were collected by 

 Charles Wright, botanist of the North Pacific Exploring Expedition, 

 known as the Ringgold and Rodgers Expedition, of which Dr. Gray gave 

 an account in a paper " On the Botany of Japan, and its Relations to 

 that of North America, and of other Parts of the Northern Temperate 

 Zone," presented to this Academy, December 14, 1858, and January 

 11, 1859, and published, April 25, 1859, in the sixth volume of the 

 Memoirs. This memoir raised his reputation to its highest point 

 vol. xxiii. (n. s. xv.) 22 



