INTRODUCTORY EXPLANATIONS. 49 



may be mentioned in Empetrum nigrum, Rubus saxatilis, 

 Trolliiis europaeus, Geranium sylvaticura, Trientalis euro- 

 paea, Habenaria albida, Ligusticum scoticura and Lilho- 

 spermum maritimum. 



4. Highland Type. — This may be considered the boreal 

 flora in a more intense degree, as respects climate, than 

 that of the Scottish type. The species referred hereto are 

 distinguished from those of the Scottish type by being 

 more especially limited to the mountains or their immedi- 

 ate vicinity. Some of them are wholly confined to the 

 higher mountains, and never descend within the agrarian 

 region ; these being the ' arctics ' before mentioned on 

 page 54. Others, though prevalent on the mountains, do 

 descend also into their glens and valleys quite within the 

 agrarian region. And others, again, may occasionally be 

 seen outside the mountainous tracts, particularly along 

 the course of rivers which have their sources among the 

 mountains, or even upon the rocks of the sea-coast. As a 

 group, these species are either restricted to the mountains 

 or very decidedly more prevalent there. Several of them, 

 more especially the true arctics, are strictly peculiar to 

 the Highland mountains ; while others occur also on the 

 mountains of England and Wales, though less plentifully 

 than in the Highlands of Scotland. The name chosen for the 

 type intimates their most appropriate habitat, although 

 some of them do likewise find a suitable climate on the 

 mountains of England or Wales. It is probable that the 

 Highland type will comprehend about a fifteenth of the 

 whole flora of Britain ; its species scarcely reaching a 

 hundred. But if we should unite the Highland and Scot- 

 tish types, as one boreal type in contrast against the aus- 

 tral or English, they would together constitute about an 

 eighth of the species now fairly wild in Britain. As ex- 

 amples of thoroughly Highland species, such as do not 



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