THE AZORES 



409 



to the " retama " (Spartocytisus nubigenus), a broom, which with 

 occasional herbs reaches to nearly 11,000 feet. So characteristic 

 is the broom of this elevated region that the pumice plains are known 

 as the " Llano de la Retama." 



Before contrasting the zones on Teneriffe with those on Madeira 

 and in the Azores, we will first determine what we ought to expect, 

 having regard to the difference in latitude (Teneriffe, 28° 17' N. ; 

 Madeira, 32° 44'; Pico, 38° 28') and the associated differences in 

 climate. From the data given below it will be apparent that in 

 response to the cooler climatic conditions we should expect in the 

 case of Pico no African zone, and in its place the extension of the 

 Laurel woods to the coast. In the case of Madeira we should look 

 for intermediate features in the vertical range of the zones. The 

 African zone would be considerably restricted, and the lost ground 

 would be occupied by the Laurel woods in their descent towards 

 the coast. 



Taking the rate of change of the mean temperature at rather over 

 three degrees, Fahrenheit, for each thousand feet, the difference in 

 the annual mean temperature near the sea-level at Teneriffe and 

 Pico, which is about seven or eight degrees (69-61), would represent 

 some 2000 or 2500 feet. From this it follows that the warm climatic 

 conditions that prevail below 2000 or 2500 feet on Teneriffe, or, in 

 other words, those of the African zone, would not exist on Pico; 

 whilst the Laurel woods, which succeed the African zone on Teneriffe, 

 would on Pico descend to the coast. In the case of Madeira, where 

 the mean annual temperature near the sea-level (about 66° F.) is 

 some three or four degrees lower than at Teneriffe, the corresponding 

 difference in altitude would be 1000 or 1200 feet. As the result, 

 the upper limit of the African zone in Madeira, instead of lying 

 2000 or 2500 feet above the sea, as on Teneriffe, would only attain 

 half that elevation on the Madeiran slopes, and the Laurel woods 

 would descend to a similar extent. 



When we come to the facts, and compare in the first place the 

 zones of vegetation on Teneriffe and on Pico, the results may soon 

 be stated. Pico owns no African zone. Where the cultivator has 

 allowed it, its lower woods so Canarian in their character, in their 

 Laurels, their Fayas, and their Tree-Heaths, instead of lying some 

 2000 or 2500 feet up the slopes, as on Teneriffe, descend to the vicinity 

 of the coast. So also its upper woods, where the Azorean repre- 

 sentatives of the Canarian Juniper (J. oxycedrus) give character to 

 the vegetation, indicate a similar downward displacement of some 

 2000 feet or more, as compared with the elevation of the original 

 Juniper zone on Teneriffe. The Canarian Juniper zone evidently 

 lay above 4000 feet; whilst the Azorean zone of Junipers descends 

 to 2000 feet. 



But there is no belt of Pines on Pico. It cannot be argued that 

 the suitable soil- conditions and the requisite elevation for the genus 

 would not be found on the barren slopes of lava and cinders on the 

 higher levels of the mountain, since from the association on Teneriffe 

 of the Canarian Pine with Juniperus oxycedrus it is apparent that 

 the place of the Pine on Pico would be at elevations 2000 or 2500 



