II] GEOGRAPHICAL DISTRIBUTION 37 



we gather the American Pipe Wort is fringed with 

 Pyrenean Heathers. The cracks which are filled with 

 the delicate green foam of the maiden hair are set in 

 Bearberry and Spring Gentian ; Hahenaria intacta, 

 far from its Mediterranean home, sends up its flower- 

 spikes through carpets of mountain Avens ; and 

 St Dabeoc's Heath and the dwarf Juniper straggle 

 together over the rocky knolls '(25). 



The presence of Eriocaulon on the western edge 

 of Europe may be attributed to migration in pre- 

 Glacial days from North America by way of a land- 

 connexion, of which Greenland and Iceland represent 

 surviving portions. The opinion held by Forbes, and 

 advocated by some later naturalists, that the southern 

 companions of Eriocaulon in the west of Ireland are 

 survivors from a Tertiary flora which have lived 

 through the Ice Age, is consistently extended to the 

 Pipe Wort. On the other hand, before yielding to 

 the temptation to regard these American and Medi- 

 terranean species as links with the Tertiary period, 

 we must be convinced that the possibilities of 

 post-Glacial introduction, even without the aid of 

 land-bridges, have been exhausted. The Pipe Wort 

 is a botanical puzzle which affords a good example of 

 the accession of interest to field-botany effected by a 

 knowledge of the distribution of the component 

 members of the British flora. The problem of its 

 past history suggests an experimental enquiry into 



