THE COMMON ALDER. 887 



is used without Urst converting it into charcoal. The bark is 

 used for tanning. 



h. Distribiifion. 



It is found in most parts of Europe, ahnost up to 02° of 

 latitude, in Northern Africa, and in Western and Northern 

 Asia. It is indigenous in Great Britain and Ireland. It 

 goes up to 1,600 feet in the Scotch Highlands, and to about 

 4,000 in the Alps. 



c. Localitij. 



Climate. — Alder requires little warmth, is fairly hardy 

 against frost, but very sensitive to drought. It is a light 

 demanding tree, standing about on a par with elm, but some- 

 what below oak. It requires moist air, and suffers from snow 

 and rime, which break the branches. 



Soil. — Alder requires a porous, moist soil of at least 

 middling depth. Moisture is specially wanted in the sub- 

 soil. Although it requires more moisture than the commoner 

 forest trees, it does not thrive in stagnant water. It is at 

 least moderately exacting as regards the chemical composition 

 of the soil. It does best on sandy loam rich in humus, and 

 thrives even on peat soil ; cold clay and dry sand do not suit 

 it. Alder is principally found along river banks in the low 

 lands, and at the bottom of mountain valleys. It does not 

 seem to be particular about aspect. 



(1. Shape and Developmeai. 



Alder develops a straight stem, which divides only in the 

 upper part ; the branches are of moderate size, with a rather 

 thin foliage. The root system consists of a number of deep 

 going side roots, which branch in the subsoil and end in 

 numerous fine rootlets. 



It is a quick grower, but rarely reaches a height of 75 feet, 

 generally considerably less ; it lives, as a rule, to an age not 

 exceeding 100 years, only exceptionally longer. 



s. z 



