BRITISH FOREST TREES 311 



Britain from the Continent and from North America. 

 Some doubt exists as to the grey or common white poplar 

 being a native of Britain ; the only species which is 

 undoubtedly indigenous is the aspen, and with reference 

 to it principally the following details apply. 



Distribution. The aspen is found over the greater part of 

 Europe, and is a characteristic tree of the plains, becoming 

 more frequent, and attaining its best development, towards 

 the north, north-east, and east ; it ascends, however, the 

 mountains of central Germany to about 3,150 feet, the 

 Riesengebirge and Baierwald to over 4,000 feet, and the 

 Bavarian Alps to 4,400 ft. It is likewise indigenous through- 

 out Asia Minor and the Caucasus, the whole of northern 

 Asia, and also in North America. On the low tracts south 

 of the Baltic it covers large forest areas with the lime as its 

 chief associate, and there often attains a height of 100 to 

 no feet, with a girth of over six feet. Much loftier growth 

 and larger dimensions are, however, attainable in England 

 by the black and grey poplars. In Scotland the aspen 

 extends northwards to the borders of Sutherlandshire, and 

 has been found by Selby at an elevation of 1,600 feet, on 

 Braemar and in Argyllshire. It occurs extensively in the 

 Norwegian and Swedish forests, and is principally used 

 there in the manufacture of the celebrated safety match..-* 

 (Taendstickor). 



Tree-form and Root-system. It develops a tall, straight, 

 full-wooded stem carrying a low-pitched, lightly-foliaged 

 crown of moderate dimensions, except when forced by 

 stony soil to spread in breadth at the expense of height, 

 borne by comparatively few branches, which, however, are 

 strong, and subdivide with considerable regularity. When 

 grown from shoots or suckers, it seldom attains the same 

 lofty development as when grown from seed, but, even in 

 the pole-stage of growth, shows signs of decreased vitality 



