The Origin of our British Flora 



Here were stretches of glacial boulder-clay, which is, 

 as every gardener knows, one of the most heart-breaking 

 and ungenerous of soils ; there perhaps bare sand with 

 only a colony or two of penguins (chiefly dead) to 

 improve its aridity. In another place estuarine mud, 

 where the sea-lions wallowed, or great stretches of gravel 

 or shingle. On the hills, bare rock and screes of rough 

 stones, in the valleys a multitude of wild water-courses 

 carrying destruction and death to every living plant or 

 animal during the autumn or spring floods. 



There would surely be a heavy rainfall, long mournful 

 weeks of cold saturating fogs ; in winter a continual 

 series of blinding blizzards ; furious gales even in 

 summer time, whilst in the higher hills there were still 

 the shrunken remnants of former glaciers. It was of 

 course impossible for such a country as this to be occu- 

 pied straight off by our ordinary British plants, even if 

 their seeds were at once available and in large quantities, 

 which was not the case. The process must have been 

 very slow and gradual ; lichens, mosses, and arctic- 

 alpines must have pioneered the way and only gradually 

 extended from South to North, and from the seashore 

 to the hill-tops. 



In Northern Europe (at least in Norway, Sweden, 

 Denmark, Schleswig-Holstein, North Germany, and 

 Prussia) four invading floras have been distinguished 

 which follow after each other, and appear to be still 

 proceeding northwards on the track of the retreating 

 glaciers.'^' 



There are, first, the Dryas flora, which is a high arctic, 

 or arctic-alpine, open flora such as now occurs in 

 Northern Lapland ; second, birch and aspen thickets ; 

 third, woods of Scotch pine, and fourth, oak forests. 



As regards the Dryas flora, it consisted of, e.g., little 

 dwarf willows (Salix polaris, S. herbacea, S. reticulata, 



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