586 DISTRIBUTION OF PLANTS IN BRITAIN. 



geography of British plants, in his earlier works gives the following 

 distribution in ascending regions : 



1. The Region of the Plains. This includes nil the low and open country from 



the south coast of England to the borders of the Highlands, in lat. 56- 

 56^, terminating at the sea level on the shores of the Clyde and Tay. It 

 contains the common weeds and wild flowers of the country, and among 

 trees, the Oak, Ash, &c. 



2. Upland Region. This is marked by the occurrence of Vaccinium Vitis-Idsea, 



Arctostaphylos Uva-Ursi, Polygonum viviparum, Trientalis europsea, Lin- 

 na boreal is, &c. 



S. Median Region. A narrow belt just above the upper limit of cultivation, 

 and the growth of Amentacere such as the Oak and Hazel. 



4. Subalpine Region. This commences at from 1,500 to 2,400 feet above the 



level of the sea. Juncus trifidus, Saxifraga nivalis, and Gnaphalium su- 

 pinum occur here. 



5. Alpine Region. This region is only truly seen in Scotland. Saxifraga cer- 



nua and rivularis, Draba rupestris, Luzula arcuata, Stellaria cerastoides, 

 and Alsine rubella, may be said to characterize it. 



Of late years, Mr. Watson has proposed the following geographical 

 division of British plants : 



1. Agrarian. Plants found only within the limits of cultivation, or within the 



limits of Pteris aquilina, in waste land the elevation or climate of which 

 would not forbid successful cultivation. 



2. Agro- Arctic. Plants found within the region of cultivation, and also above 



these limits. 



3. Arctic. Plants found only above the limits of cultivation. 



1164. In considering the distribution of British plants in connection 

 with geographical or local position, Watson suggests the follo\ving 

 types: 



1. Atlantic type: embracing species found in the south-west of England and 



Wales, as Erica ciliaris, Sibthorpia europsea, and Euphorbia Peplis. 



2. Germanic type : including species chiefly seen in the south-west of England, 



the chalk plants, as Phyteuma, Ophrys, Hippocrepis, and Onobrychis. 



3. The English type: consisting of species chiefly or exclusively found in Eng- 



land, and decreasing in frequency northwards, as Acer campestre, Tamus 

 communis, Iris fcetidissima. Orchis Mono. 



4. British type : comprehending species widely spread over Britain, as Bellis, 



Calluna, Corylus. 



5. Scottish type : embracing species prevalent chiefly in Scotland, or the north 



of England, as Trollius, Linnsea, Andromeda, Primula farinosa. 



6. The Highland type : containing species either limited to the Scottish High- 



lands, or extending to the mountains of the north of England and Wales, 

 as Salix herbacea. Azalea, Arctostaphylos, Lobelia, Subularia. 



7. Hebridean type: composed of a few species peculiar to the extreme north 



and west of Scotland, or at least chiefly seen there, as Eriocaulon septan- 

 gulare, Ajuga pyramidalis, Primula scotica. 



1165. Professor E. Forbes has adopted Mr. Watson's view. He 

 thinks that the vegetation of the British islands may be said to be 

 composed of five floras: 1. A west Pyrenean, confined to the west of 

 Ireland, and mostly to the mountains of that district. 2. A flora re- 



