Alpine and Arctic Floras 
Now, in those splendid monographs inspired and 
edited by Professor Engler of Berlin, one often finds 
very interésting studies upon the travels and changes of 
special forms, 
There was a circumpolar or rather North Polar 
flora in very ancient times. When during the great Ice 
Age this arctic flora advanced southwards and spread 
over most of middle Europe, it was invading a region 
already occupied. The plants of the older geological 
period seem to have been very much the same every- 
where, from Spain by the Alps and Asia Minor to the 
Caucasus, and even to Japan. 
The different mountain groups were isolated by this 
invasion, and one finds little sets of alpine species 
belonging to each group. 
So in, for instance, the Balkans, there are four 
different kinds of alpine flowers. There are both 
stranded relicts of the circumpolar flora, left in the hills 
when the ice retreated, and also special endemic species 
which have formed themselves in these mountains only. 
Besides these some of the alpines seem to be de- 
scendants of plants of the steppes or dry grass plains 
of South Russia, and which have invaded the mountains. 
Another group consists of Mediterranean plants which 
also have ascended and settled themselves in the hills.® 
The history of the woodrushes or Luzulas has been 
carefully worked out by the best living authority.° 
Round the North Pole one species, Luzula spicata, is 
found in northerly latitudes almost everywhere. Another 
species, L. racemosa, derived from the northern group, 
extends by the Rocky Mountains to Mexico and has 
evolved into several species in the Andes. Luzulas 
have also reached the Himalayas. Even in the Abys- 
sinian highlands there is L. abyssinica, and so far south 
as Kilimanjaro there are two peculiar species which 
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