66o 



A TEXTBOOK OF THEORETICAL BOTANY 



Fossil wood known as Pityoxylon, which is essentially similar to pine wood, 

 can be traced back to the Carboniferous times, so that a direct connection of 

 Pimis with the Cordaitales is not improbable. 



The Scots Pine is frequently found growing in this country, where it 

 forms a tall forest tree up to lOO ft. high (Fig. 659). Although at the present 

 day it is only truly native in Scotland, so far as Britain is concerned, it was 

 formerly native in England, and has been extensively planted since the 

 eighteenth century. 



Native Pines generally grow gregariously, forming rather open forests. 



Fig. 659. — Pimis sylvestris. In Langdale, Cumberland. 



Isolated specimens are sometimes seen, especially on wind-swept heights, 

 where their original shape is frequently altered by the influence of the pre- 

 vailing wind and they become dwarfed and bent. Only a few scattered remains 

 of the great Caledonian Pine forest are to be found in the Scottish Highlands, 

 which were densely forested in former ages, as Scandinavia is to-day. 



The tree possesses a tap root growing straight down into the soil, but in 

 most examples this tap root disappears at an early stage and is replaced by 

 lateral roots, which form a massive root system. It may be that this is 

 partly accounted for by the fact that the tree frequently grows on shallow soil 

 overlyng rock where it would be impossible for a tap root to penetrate. In 

 any case we generally find that the rooting system of the Pine is spread out 

 over a large area, but that none of the roots penetrates very deeply into the soil. 



