INTRODUCTION. 27 



The Fruticosc Rubi do not ascend to a great elevation 

 above the level of the sea. Mr Watson {(Jompend. of Cyh, 

 Britan. 19) considers their upper limit to be in his Huper- 

 agrarian zone, which is characterized by tlie presence of 

 Qiiercus, Frax'inus, Lonicera and Cratcegus, and by the 

 presence of Pterin witliout Rhamnus. 



In the vale of Llanberis in North Wales 600 feet is 

 about the height at whicli they aj)pear to cease. Below that 

 elevation they are immediately plentiful; above that I 

 only noticed one bush [R. discolor), whicli was growing 

 under a wall at the great height of 1000 to 1100 feet ; but 

 as no others occurred, its existence there was probably the 

 result of accident. Mr Lees {Bot. of Worcest. p. 142) states 

 that " In general Ruhi delight in hilly spots of moderate 

 height, becoming prostrate... at above 2000 feet of elevation, 

 but descending and luxuriating even on the sands of the 

 sea-shore." It is therefore possible that the elevation which 

 my observation has led me to adopt as the upper limit of 

 their growth is too small, especially as Mr H. C. Watson 

 gives 900 ft. as the highest point at which they are found 

 in the West Highlands of Scotland, and Mr Baker about 

 the same elevation in the Humber and Tyne Districts. It 

 would be interesting to ascertain if the R. suherectus which 

 Mr Lees informs me that he found near " Gors Lwm on 

 Banwen" Mountain in Glamorganshire, at an elevation of 

 about 2000 feet, is the true plant, or is not rather the 

 R. fissus. I have never noticed R. suherectus on exposed 

 spots such as that must be, but have often seen R. fissus 

 on open mountain sides, although never at so great an 

 elevation. R. fissus is the R. suherectus of many recorded 

 stations, especially of those in Scotland. 



