210 BEITISH PLANTS 



The past history of the British flora, then, is part and 

 parcel of the history of the flora of Northern Europe. 

 The population of this region with its present plants 

 dates from the close of the Ice Age. During the Glacial 

 Epoch Northern and Central Europe were completely 

 buried beneath a sheet of ice, much as Greenland is 

 to-day. The vegetation previously existing was de- 

 stroyed or driven south into Northern Africa, which was 

 then connected with Europe by several land -masses 

 stretching across what is now the Mediterranean Sea. 

 As the Ice Age passed away, and warmer conditions pre- 

 vailed, the ice melted, and the bare earth became ex- 

 posed. A great host of advancing forms moved north- 

 ward in the track of the retreating glaciers, and repopu- 

 lated the abandoned territories. At flrst the soil, so 

 recently relieved of its icy burden, provided but a poor 

 habitat for plants. The cHmate also was still very cold. 

 The pioneers of the migration were those plants which 

 were fitted to endure the greatest hasdships. At flrst 

 they had no competitors. The struggle for existence was 

 not with one another, but with the hardships of their 

 environment. But as time went on, and climatic condi- 

 tions improved, fresh invaders appeared in the territories 

 prepared by the pioneers ; fierce competition ensued, and 

 while some seized, as conquerors, the pleasant places, 

 others perished or survived only in less favoured habitats 

 where competition was not so keen. In the struggle the 

 pioneers were the first to suffer. Adapted to live, un- 

 molested by competitors, in cold or alpine conditions, 

 they were unable to compete successfully with their rivals, 

 and before the advance of lowland and temperate forms, 

 this vanguard of the northern plant-migration was 

 restricted to the mountains, where its descendants stiU 

 remain. 



The alpine flora of Europe is almost the same every- 

 where. The same flowers grow on the mountains of 

 Wales and Scotland as on the Scandinavian highlands, 

 the Alps, and the Pyrenees. Stranger still, the alpine 

 flora of Africa, America, and even Australia and New 

 Zealand, differs little from our own — so little, indeed, 

 that some have suggested that the Scandinavian flora 

 once dominated the earth, and that its remnants survive 

 upon the highlands everywhere to this day. 



