II] GEOGRAPHICAL DISTRIBUTION 23 



their Alpine species have in large measure been 

 derived from non-glaciated parts of the Pyrenees, that 

 is from a region which was presumably able to retain 

 its flora at a time Avhen more northern lands were 

 exposed to extreme Arctic conditions. My friend 

 Dr Moss believes that some of the so-called Scandi- 

 navian plants came to Britain from Central Europe 

 after the retreat of the ice ; if this view is correct it 

 means that some at least of our iVrctic-Alpine plants 

 reached these islands by a southern rather than by 

 a northern route. 



Interesting examples of far-travelled northern 

 plants recently described by Professor Engler of 

 Berlin afford additional illustrations of the general 

 principles enunciated many years ago by Sir Joseph 

 Hooker. A species of flowering Rush, Luzula 

 spicata var. simensis, occurs at an altitude of 3600 

 metres in Abyssinia and on Kilimanjaro. Luzula 

 spicata is found in the whole of the Arctic and 

 Subarctic belt in Scotland, Auvergne, the Jura 

 mountains, and elsewhere. The species probably 

 began its career in the northern hemisphere where 

 it grew abundantly on the higher ground in the 

 Arctic Circle : it eventually travelled along the 

 North American Andes and appeared in Mexico 

 under a guise sufficiently distinct to warrant the 

 use of another name, Luzula racemosa. In an 

 eastern direction it reached the Himalayas and is 



