HAltL> W iCKE'S SCIENCE-GOSSIP. 



73 



ALPINE PLANTS. 



.^ HE botanist who 



is well acquainted 



with the Flora of 



his own counlry 



may often be 



puzzled by the 



diversity of forms 



and multiplicity of 



species in the 



Alpine Elora. Tlie 



following speculations which 



we venture to give, based on 



known facts, may, therefore, 



not be uninteresting. 



Alpine plants may be divided 

 into three classes": 1st. Those 

 found exclusively in moun- 

 tainous regions. 2nd. Those 

 found also in high northern 

 latitiides. 3rd. Those closely 

 allied to species which grow in 

 the plains. Let us see what 

 is the origin of these three 

 classes. 

 That the geological period 

 preceding the glacial epoch was one of considerable 

 heat is shown by the fossil plnnts found in the 

 Miocene formations of Greenland. The advance of 

 the glaciers gradually destroyed most of the vegeta- 

 tion of tin's period : some of the original denizens of 

 the mountains remained, however, on high ground, 

 not covered by snow and ice ; but the altered con- 

 ditions of life were not favourable to their develop- 

 ment, and they are now few in number, frequently 

 monotypic, and found in a limited range. Sue!) are 

 the genera 





A . 



The glaciers brought with them plants and seeds 

 from the Arctic regions, and these established them- 

 selves on the higher summits. The varieties of 

 climate and geological formation in the gi'eat moun- 

 tain-chain which extends from Spain to Siberia are 

 considerable. These influences would modify these 

 northern plants, and in course of time would even 

 cause the formation of new species, so that they now 

 outnumber, both in species and individuals, their 

 Arctic congeners, whose development has been re- 

 stricted by a narrower area and uniformity of climate. 

 A curious fact bearing on the origin of these plants 

 is that comparatively dry mountain-ranges, such as 

 the eastern Alps, which have a climate somewhat 

 similar to that of the cold, dry Arctic regions, are 

 richer in species than more humid ranges, such as 

 the Bernese Oberland and Scotland. Some of the 

 principal genera of this, our second class, are 



That the temperature of the Alps has varied con- 

 siderably since the glacial period is shown by the 

 alternate advance and retreat of the glaciers. Le- 

 gends exist of once fertile valleys in spots which 

 are now covered with snow and ice, and it is said 

 that the great ice barrier betv/een Grindelwald and 

 the Valais was formerly a much-frequented pass. 

 Duringsuch favourable periods plants fromtheplains 

 may have been gradually dispersed upwards, and 

 mingled with the Flora of the former glacial period. 

 There is very little doubt that large seas existed at 

 the foot of the Alps, and this will account for the 

 coast plants that arc also found as Alpines, such as 

 Flaiiiago alpinci, Armeria alpina, and RJiodioIa 

 rosea. 



AH these plants, which forai our ihird class, have 

 been mucii modified by mixing with the more 

 ancient forms ; they have also become dwarfed in 



E 



