The Origin of our British Flora 



to-day, and worse than it was in the same district at an 

 earlier date, when birches grew in the same place. Such 

 peat-mosses show a succession of deposits as follows : — 



Recent or Youngest 7. Peatmoss, Sphagnum. 



6. Pine forest or Upper Forest. 



5. Peat bog plants or Upper Peat bog. 



4. Arctic plants or ^nd Arctic^ Empetrum. 



3. Peat bog plants or Lower Peat. 



2. Birch or Lower Forest. 



Oldest Deposit i. \st Arctic or Dryas flora.** 



From Mr. Clement Reid's papers, and especially his 

 *' Origins of the British Flora," we know not only a large 

 number of the plants w^hich were found in Britain during 

 the Ice Age, but also a large number of preglacial 

 plants. 



Even at that distant date, chickweed. Polygonum 

 persicaria, meadow-sweet and hawthorn were living in 

 England. The alder and bogbean (Menyanthes) were 

 not only preglacial but occurred in all the deposits down 

 to those of Neolithic age. There are many signs of the 

 warmer and milder character of the interglacial period 

 which, as we have seen, is indicated even in Scotland. 

 Trapa natans is now no longer British, though it 

 grew near Cromer before the Ice Age. Indeed, what 

 strikes one most from these lists is how little and 

 not how much difference was caused by the great ice 

 invasions. 



It is a very pleasant duty to recognise the extremely 

 valuable nature of these discoveries, which have in- 

 deed explained the past history of the British flora in 

 a very satisfactory way. The British botany of to-day 

 may indeed be proud of these researches, though 

 there are of course many doubtful points as yet un- 

 explained. 



Dr. Lewis has compared his results with Professor 



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