l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



to be of the same age. The Jackson flora reaches Latitude 2)7^ North. 

 The most similar existing flora to that of the Jackson does not extend 

 above Latitude 26° North, and then only under especially favorable 

 conditions of situation with respect to warm ocean currents. This is 

 a difference of 11 degrees. The flora of the Jackson was, moreover, 

 a coastal flora, and I have not the slightest doubt but that had the 

 Mississippi embayment extended five degrees farther North, its shores 

 would have been clothed with the same Jackson flora, for at that time 

 similar floras are found in the Paris Basin in Latitude 49° North, 

 in southern England in Latitude 51° North, and along the expanded 

 Mediterranean sea of the Old World. 



The southern limit of the contemporaneous " Arctic flora " is about 

 Latitude 45° North in North America (British Columbia), and about 

 57° North in Europe (Isle of Mull). It seems to me that the essential 

 concordance of these facts is significant, and whatever may be thought 

 of them, it would certainly seem to be difficult for any one to claim that 

 these various Eocene floras mentioned do not show a climatic change 

 in passing northward from the equator toward the pole. Moreover, at 

 present — a time of. in many ways, an abnormal climate in a geologic 

 sense ; with rather sharp zoning, although not nearly so sharp as the 

 textbooks would have us believe; a time of almost, if not quite, un- 

 precedented land expansion in the Northern Plemisphere, which I 

 believe expresses a casual relationship — the reliable members of these 

 Eocene Arctic floras range much farther southward than they did 

 in late Eocene time. 



EXISTING ARCTIC FLORAS 



Greenland is the most illuminating of Arctic Lands because it is 

 much the largest, and therefore more likely to preserve endemic 

 species, and to receive immigrants from other Holarctic lands. Al- 

 though mostly covered by ice which rises to an altitude of more than 

 8,000 feet in the interior, it has island peaks (nunataks) with recent 

 plants. Moreover the northeastern part appears never to have been 

 glaciated. 



About 400 species of recent vascular plants have been recorded 

 from Greenland and at the south trees may reach heights of 10 or 

 12 feet. North of the Arctic Circle the number of plants is fewer, 

 but Ostenfeld (1925) records 125 species north of Latitude 76° and 

 108 between Latitudes 78° and 80°, including 2 equisetums, a lycopod, 

 3 ferns, 32 monocotys and 70 dicotys, including Salix and Vaccinium. 



In an earlier paper (Ostenfeld, 1923) this author describes the flora 

 of the north coast and records 70 species of plants from Latitude 82°. 



