276 23. LEGUMINOS^. 



in every case be shown to have been introduced into Ork- 

 ney, and not to be an indigenous plant." Balfour and 

 Babington say, "planted and thriving near Barvas, in 

 Lewis," one of the Hebrides. In the north of Caithness 

 and Sutherland, I observed it in several places, apparently 

 wild, but it might have been sown or planted in the locali- 

 ties. The late Professor Graham thought it indigenous in 

 Strath Naver, in Sutherland, where it occurs, he says, as 

 " detached plants throughout the whole Strath, about 

 twenty mUes long." From this pecuUarity of its growth, 

 whether native or naturalized, we may infer that the clima- 

 tic limit is there neajrly attained ; that is, where it ceases 

 to have the vigom* of growth and reproduction which ena- 

 bles it to become social on the commons of England, by 

 choking and banishing most other plants. Although in 

 one spot, on the south-east declivity of Camedd David, 

 seen 'so high as 700 yards, yet the more usual or natural 

 limit runs nearer to 450 or 500 yards in North Wales. 

 Winch says that it attains 650 yards in the north of Eng- 

 land. Near Mr. Ogilvie's Shooting Cottage, on the Clova 

 mountains, I obsen^ed it at 500 yards of altitude ; but pro- 

 bably planted there. It may be seen sparsely near the 

 Dee, above Castletown, say at 400 yards ; though near the 

 sites of former cottages. Occurs in Glen Clova, at 250 or 

 300 yards. I have estimated the lower extreme of the 

 range of temperature, on the supposition of 600 yai'ds 

 being the limit in elevation, for the latitude of North 

 Wales; the high elevation of 700 yards having been in a 

 pecuUaily favourable aspect. The Irish U. strictus is re- 

 tained as a species by Mr. Babington, though now aban- 

 doned even by its original proposer, Mr. Mackay. It is a 

 peculiar form, which is rather a monstrosity than a vai'iety ; 

 but is propagated by seed, like many other varieties and 



