Fortunate Islands 



acteristic rock and dry climate plants not found else- 

 where. 



At those heights from 1500 feet (or on the S.W. and 

 S.E. 2500 feet) to 5000 (or 4000 on S.W. and S.E. sides), 

 where the clouds are still in the habit of resting so as 

 to keep fresh and moist the gathering grounds of the 

 springs which irrigate the lowlands, the changes have 

 been very great. This is the home of Laurus canadensis, 

 of Olives, Rhamnus, Arbutus, Myrica faya and Viburnum. 



It is a strange flora which recalls, perhaps better than 

 any other still living, the old Miocene times of Europe 

 before the Ice Age disturbed everything. This part has un- 

 fortunately been much altered by the grazing of animals 

 and much of it is now covered by those gum-cistus 

 heaths which are prevalent in Spain and Portugal. The 

 coniferous forest (Pinus canadensis) is also much de- 

 stroyed and almost obliterated, yet from 5400 to 7800 

 feet occasional pines exist along with bracken, thyme, 

 helianthemums, and the common asphodel. Above 

 this level, where the influence of the cloud is rarely felt, 

 there comes a dry and sunny mountain-desert where 

 Spartium nubigenum, Cytisus proliferus, Arabis albida 

 and Ephedra may ascend to 9850 feet. 1 The last 

 flowering plant is the little violet discovered by Von 

 Humbolt. 



This, the highest part of Teneriffe, resembles the 

 cold dry deserts at great altitudes in Tibet and in Peru. 



The general suitableness of all these various floras to 

 their positions on the mountain side is a typical and 

 most instructive example of Nature's workings. 



The way in which the South Sea Islands obtained 

 their rich and varied floras is always interesting but by 

 no means fully understood. 



It is not always remembered that two things are 

 necessary when a desert island has to be colonised. The 



276 



