DISTRIBUTION OF PLANTS IN BEITAIN. 



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Considering Britisli plants in climatic or ascending zones they are 

 divided by Watson into — 



I. Ageaeian Eegion — limited generally by the Pteris aquilina, 

 and indicating the region of Corn cultivation. In the High- 

 lands it may be said to extend as high at least as 1200 feet. 



It is subdivided into three zones : — 



1. Infer-agrarkm Zone — embracing all the country southward from 



the Dee and Humber, except the mountamous parts of Wales, 

 and the higher hills and moors in the provinces of the Severn 

 and Peninsula (including.GIoucester, Worcester, Warwick, Staf- 

 ford, Hereford, Monmouth, Cornwall, Devon, and Somerset). 

 Some of the peculiar species are Clematis Vitalba, Eubia pere- 

 grina, Cyperus longus, Erica cUiaris, Sibthorpia europ^a, and 

 SciUa autamnalis. 



2. Mid-agrarian Zone — all the low grounds, clear from the mountains, 



situate between the entrance of the Clyde and Tay on the north, 

 and :those of the Humber and Dee on the south, also probably a 

 narrow coast-line of the East Highlands, extending from Perth 

 to Aberdeen, and possibly even to Inverness. Also a narrow 

 belt extending round the hills of Wales. Bhamnus catharticus 

 and Fraugula, Tamus communis, Bryonia dioica, Acer cam- 

 pestre, Ulex nanus, Viburnum Lantana, Euonymus europseus, 

 and Cornus sanguinea, occur in this zone, but are not restricted 

 to it. There is no Clematis. 



3. Super-ayrarian Zone — coast-line and low plains and moors in the 



north and ' north-west of Scotland, where alpine plants descend 

 to the sea-shore ; such as Thalictrum alpinum, Draba incana, 

 Saxifraga oppositifolia, Arotostaphylos alpina, and Dryas octo- 

 petala. Also other parts where the elevation of the ground leads 

 to the production of the same species, or of such plants as Aroto- 

 staphylos Uva-Ursi, Saxifraga stellaiis, AlchemUIa alpina, 

 Tofieldia palustris, Juncus triglumis. Also tracts of slight 

 elevation in the proximity of high mountains, upon which a 

 corresponding flora prevails. At its lower limits appear Ilex, 

 Corylus, Quercus, Fraxinus, Lonicera, Crataegus and fruticose 

 Rubi. 



