71. AMENTIFEK^. 407 



nearly all the Highland mountains which exceed 700 or 

 800 yards in altitude, and is also plentiful at similar eleva- 

 tions on the rocky acclivities and by the streams of those 

 which attain 1000 yards or upwards. In the province of 

 East Highlands, the lower line of Salix herbacea may be 

 considered to run between 700 and 800 yards, descending 

 even below 700 yards in some few places ; but the plant is 

 seldom found plentifully before we have attained to 800 

 yards. In the West Highlands, as about the Ben Nevis 

 grou]), we may take the lower line or limit at full 50 yards 

 lower than in the East Highlands. And in Orkney, the 

 dwarf willow must grow as low as 500 yards, or thereabouts; 

 since it is reported to occur on Hoy Hill, which is consi- 

 dered not quite 1600 feet of elevation. As it is stated to 

 gi'ow on Ingleborough, in Yorkshire, it must descend below 

 800 yards in England. Our British mountains are not 

 sufficiently lofty to show the natural limit of Salix herbacea 

 in an upward direction. It attains the summit of the high- 

 est mountains of Scotland, the bare and rocky top of Ben 

 Nevis excepted ; where the want of soil, and not the alti- 

 tude merely, may be assigned as the cause of its absence. 

 The only authority for this little shrub in South Wales 

 is that of Mr. Jones, in Turner and Dillwyn's Guide ; 

 which it would be desirable to have confirmed, although 

 the altitude of the Beacon of Brecon (950 yards) seems 

 sufficient to give much ])robability to the record. The ap- 

 parent absence of Salix herbacea from Shetland, where one 

 hill is high enough to support the Azalea procumbens, is 

 worthy of note in connexion with its abundance in Scot- 

 land, and its occurrence in Orkney, Faroe, &c. 



