Alpine and Arctic Floras 



Now, in those splendid monographs inspired and 

 edited by Professor Engler of BerHn, one often finds 

 very interesting 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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