ie 
in their Influence on Vegetation. 359 
L, et var. (Rape) grow as far north as there are settlements. In 
Norway beyond 70° N. L.; in Siberia to the Polar Circle; on the 
N.W. coast of America to 64° 45’ (Nulato) and Redout St. 
Michael (63° 30’); in the interior to 67° (Fort Good Hope).” 
In Greenland, Rapes, Turnips, Cabbage and Salad are culti- 
vated under 70° L. (Island Disko). 
e potato follows the above named plants in their distribn- 
tion to the north and belongs also to sea climate species. On its 
northern limit, however, in Siberia as well as in N. America, it 
reaches only the size of a walnut." In Greenland, only the 
most careful treatment can produce eatable potatoes. The plant 
never blossoms there.” 
Comparing the vegetation of the extreme continental climate 
with that of the extreme sea-climate on the globe, the continen- 
(only a grass—Atra antarctica Forst—is foun there); and on 
64° S., the last trace of vegetation is found 
(cry ptogamous plants). In this latitude north there is in Sibe- 
fe f 
Q 
(o) 
re) 
a 
= 
5% 
— 
=, 
© 
s 
7") 
tween 36° and 41°. Thus, notwithstanding the mean tempera- 
ture of June at Yakutsk is 55°, and that of July 62°,” the 
Vegetation is relatively slow,” though its period (10 to 12 
Weeks) is the same as observed in Central Europe. The same 
Period is observed in North America, under 63° (Fort Simpson)” 
of the barley. (Wheat does not come to maturity there.) But 
. 214. 18 Middendorff, p. 700. 
'® Etzel, Gronland geogr. und statistisch iierrohae opt Stuttgart, 1860, p. 282. 
under Wilkes on lat. 65° 15’, 27°60 
1852. vol. ii, p. 281. 
*' Under lat. 64° 5’ mean temp. of January, 1843, 31°; under 62°-66", in Feb- 
deta See Ross, Voyage in the Southern and Antarctic Regions, vol. ii, p. 
* Middendorff, p. 772. %8 Middendorff, p. 718. 
* Richardson, vol. i, p. 165. 
