xlii INTEODUCTIOlSr. 



Highland Type or mountain plants, tte deficiencies of the Irish flora 

 become at once more prominent. The following table, based on 

 Watson's Compendium of the Cylele Britannioa, 1870, is designed to- 

 sho-w the comparative richness of the English and Irish floras under 

 these various types. The exclusion from this table of the Highland 

 and Scottish type plants absent from England and "Wales has dimi- 

 nished the total number of these types by some 58 species. 



Representation of Watson's Botanical Types in England 

 and Wales, and in Ireland. 



The extreme poverty of the Irish flora in Germanic Type plants,, 

 or plants chiefly prevalent in the provinces of East England border- 

 ing on the German Ocean, is the most striking feature in this com- 

 pEirative table. The foUowing list shows all the species of this type 

 which can be accepted as Irish. Of the total number of 12 plants 

 in this list, four are certainly or probably introduced ; of the remain- 

 ing eight, six are rare ; and four, Astragalus hypoglottis, Limosella 

 aquatica, Qlyceria Borreri, and Polygonum mite, extremely so. 



Germanic Type Plants in Ireland. 



Astragalus hypoglottis. *Senecio viscosus. Polygoniuu mite. 



JGalium erectum. Hypopithys multiflora. Orchis pyramidalis. 



*Crepis biennis. Limosella aquatica. Glyceria Borreri. 



C. taraxacifolia. Teucrium Soordium. -f-Bromus erectus. 



Existing climatic influences would seem to have played but a sub- 

 ordinate part in producing this remarkable poverty of East England 

 plants in Ireland, or, indeed, the large deficiencies of species of the 

 English type. The main cause is more obscure, and must be sought 

 for in the geological history of the British Isles. There is a strong 

 body of evidence to show, that Ireland, as an island, is of much. 



