58 Proceedings of the Royal Irish Academy. 



-composition. The Eastern group of Ireland is seen to be essentially 

 southern in Great Britain, while the Eastern group of Great Britain is 

 practically absent from Ireland ; nevertheless the two correspond in 

 eharacter, representing in each case the nucleus of the thermophile and 

 xerophile elements of the flora — in England a much more intensified 

 group than in Ireland. The "Western plants of the two islands also 

 ■exhibit a wide diversity in range, those of Great Britain being 

 Southern and Marginal in Ireland, while those of Ireland are not 

 to any extent "Western in Great Britain, and include besides a 

 number of species absent from the sister island. But here again 

 the two have affinities, both being hygrophile and frigofuge in 

 character. The two remaining Irish types, the Central and Mar- 

 ginal, have no analogues in Great Britain. The former consists largely 

 of "English" species, the latter chiefly of " British " plants which 

 ■do not penetrate into the Limestone Plain. 



It will be observed that no type corresponding to "Watson's High- 

 land type is proposed for Ireland. Plants of this kind form in Ireland 

 a much less distinct group than in Great Britain, being largely reduced 

 in numbers, and not nearly so montane in habitat. Moreover, they 

 have not any so deflnite head-quarters as, in Great Britain, they find in 

 the Highlands of Scotland. In Ireland, plants of Highland type are 

 distributed almost equally between the Marginal, Ultonian, and Con- 

 nacian areas. None belong to the Lagenian and only one to the Mumo- 

 nian, although in those districts occui' the largest areas of high elevation, 

 as well as the loftiest summits, in the country. The actual alpine flora 

 of Ireland is extremely limited. Taking the 42 Irish plants belonging 

 to "Watson's Highland type, we find that one-third of them descend in 

 Ireland to sea-level. Sixty per cent, may be found at elevations of 

 500 feet or less. Fully one-half of the group flourish at these low 

 elevations in places where alpine ground — say over 1000 or 1500 feet — 

 does not adjoin, so that theii' occurrence means not merely the washing 

 down of seeds from their natural high-level habitats. Only 30 per 

 cent, keep above the thousand -foot contour line, only 5 per cent, above 

 the 2000-foot line. In fact, "Watson's Highland plants cannot be defined 

 in Ireland as a group " chiefly seen about the mountains." They are 

 chiefly seen in certaia hill-regions, but the presence of even high 

 mountains does not necessarily involve their appearance. The species 

 seen about the mountains are largely British type plants, with a 

 variable admixture of " Highland " species, and certaia local groups — 

 in the north " Scottish" plants, in the south often " Lusitanian." It 

 does not seem desirable to attempt to construct out of these hetero- 



