Conifers 



birch thickets and alpine plants, and their special ab- 

 sorbing Mycorhiza is no doubt well fitted to find the 

 necessary salts as rapidly as possible. Under the micro- 

 scope the appearance of some pine roots is very re- 

 markable, for they are entirely covered over by a sort 

 of webbing or felt of fungus threads. 



The distribution of conifer forests in the world is 

 particularly interesting. They begin in the north as a 

 complete ring surrounding the Pole, but at different 

 degrees of latitude. These northern woods are not, 

 however, the same. Our Scotch pine goes farthest 

 north in Scandinavia, but not in Russian Siberia, where 

 it is replaced by the fir, which seems to be able to grow 

 better on swampy, peaty ground. Beyond the Urals, 

 the Siberian larch is the most northerly tree, and 

 sometimes goes as far north as 72° 40' N. lat.^ 



Pinus cembra replaces the larch from the longitude 

 of Werchojansk to Behring Straits. In America, spruce, 

 Picea sitchensis, and Pinus contorta and Murrayana are 

 the most northern trees in Alaska, but east of the 

 Rockies it is the American larch that is the pioneer of 

 woodlands. Greenland has not any trees in the present 

 geological epoch. 



These differences are very curious and have not been 

 explained, but it is possible that the larches can best 

 withstand the continental conditions, where there is less 

 rainfall, than the pines and spruces. The pine seems 

 to prefer drier and rocky ground, and the spruce does 

 better on sodden peat and in swamps. 



The ^^ forest primaeval " of these far northern latitudes 

 is not at all impressive. The trees are scraggy, stumpy, 

 badly grown and covered with old man's beard and 

 other lichens. 



From these northern forests there are in each con- 

 tinent diverging woodlands, which take to the mountains 

 when they arrive at more genial latitudes. For, as we 



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