THE INTERIOR FOREST 239 



These general considerations will assist in understand- 

 ing the variety and changes in appearance of the Alaska 

 forest flora. 



THE INTERIOR FOREST. 



The interior of Alaska is but little known, and as a 

 rule only along the river courses. A few cross-country 

 routes have been traversed by explorers who, not being 

 botanists, leave us in doubt as to the exact species repre- 

 sented in their casual remarks on the forest conditions. 

 They generally mention spruce as the only conifer, and 

 cottonwood, aspen, birch, willow, and alder, as the decid- 

 uous-leaved species. The reference to fir and hemlock, 

 as occurring in the Yukon district, made by W. C. Green- 

 field in the Census volume of 1890, is probably an error. 

 So probably is Dr. C. W. Hayes 1 in error, when, in 

 contrasting the vegetation of the Yukon with that of 

 the coast, he says: "This contrast consists more in 

 the amount of vegetation than in the difference of 

 species." 



The account in the ninth volume of the Tenth Census 

 of the ' Northern Forest of the Pacific Region' (p. 7) is 

 extremely vague, and in the light of newer information, 

 faulty; but it attempts at least to designate the species 

 found. The statement is as follows: 



" The white spruce, 2 the most important and most north- 

 ern species of the North Atlantic region, is here also the 

 most important species. It attains a considerable size as 

 far north as the sixty-fifth degree, forming in the valley 

 of the Yukon, forests of no little local importance. The 

 canoe-birch, 3 the balsam poplar, 4 and the aspen, 6 familiar 



'Nat. Geog. Mag., Vol. IV., p. 136, 1892. 

 8 Picea canadensis (Mill.) B.S.P. 

 Betula papyrifera Marsh. 

 4 Populus balsam ifera Linn. 

 6 Populus tremuloides Michx. 



