The Origin of our British Flora 



carpon, Allium triquetrum, and perhaps the wild gladio- 

 lus, but it is very difficult to give a satisfactory list. 

 These belong to the west and south of France, Portugal, 

 and Spain, and might be supposed to represent an out- 

 lying part of the Mediterranean flora. 



They occur along the south coast of England, in 

 Ireland, and in some few cases also in the south-west of 

 Wales, which seems at first sight to be a very inexplic- 

 able sort of distribution. 



But if one takes Bartholomew's Physical Atlas (Plate 

 1 8), which gives the distribution of sunshine in the 

 British Isles (after Mr. H. N. Dixon), a very interesting 

 coincidence can be traced. The sunniest part of Britain, 

 which possesses from 1600 to 1700 hours of sunshine 

 in the year, includes very nearly all the habitats of 

 these rare Spanish plants. The line of 1600 hours of 

 sunshine cuts off Beachy Head, part of Dorset, about 

 two-thirds of the Isle of Wight, and a considerable 

 portion of south-west Cornwall and Devonshire ; it then 

 curves up to the north so as to take in a little of south- 

 west Wales, and fringes the southern Irish coastline. 

 The Irish observations seem to have been insufficient, 

 but it seems that the curious sporadic and irregular dis- 

 tribution of these peculiar southerners really does more 

 or less coincide with a sunshine amount of between 

 1600 and 1700 hours per year. 



This part of England seems to have escaped the ice 

 of the glacial period, and it is quite likely that the 

 arbutus and asparagus are relicts of the first warm and 

 dry interglacial period. But of course this is a question 

 which requires much more detailed evidence. 



There is yet another little group, the Blue-eyed grass, 

 Eriocaulon, and Spiranthes Romanzofiana, about which 

 there has been plenty of speculation and discussion. 

 The last grows in Kamschatka, and also in Bantry Bay, 



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