45f) OEOLOOICAI, SIRVEY <»K rANAMA. 



558. POPULUS, Linn. iPOPLAR.) 



(2053.) P. tremuloides, Muhx. AHpon. 

 P. In-picUi, WilUl. rnrsh. Fl. I., 018. 

 One of the most widel}' distributed of the deciduous trees. It is 

 found on :ill dry slopes from Newfoundland and Labrador throughout 

 the northern forest region to Alaska. It constitutes the "bluifs" 

 and copse wood scattered over the prairie region, and is a tine 

 large tree in the southern part of the sub-arctic forest. Although it 

 is always found on the dry slopes in the north, in Ontario it more 

 frequently grows on wet than on dry soil. 



(2054.) P. grand identa, Michx. Large-toothed Aspen. 



Rather common in many places in Nova Scotia, mixed with aspen. 

 {Macoun.) Vicinity of Pictou, N. S. {McKay.') Quite common in 

 New Brunswick. {Fowler s Cat.) A common tree in Quebec and 

 Ontario, but usually taken for aspen. It generally grows on sandy 

 soil, intermixed with young pines. 



(2055.) P. balsamifera, Linn. Balsam Poplar, 



This ti-ee, in habit, differs very much from the aspen, but in its 

 range it extends even farther north, and instead of being of little value, 

 as the aspen is, it attains a great size and height, as far north 

 as the arctic circle on the Mackenzie Eiver. West of Manitoba 

 and northward, it is usually found growing on alluvium in the river 

 valleys, and in such situations it is often nearly 150 feet high, and 

 frequently over seven feet in diameter. On the Peace River and 

 all streams which unite to form the Mackenzie, it occupies all the 

 islands and low alluvial banks. During the period of flood many trees 

 fall into the rivers by the wearing away of the banks, and a great 

 number of them in the course of time reach the Arctic Ocean. These 

 are eventually cast on the islands and shores, and become the chief 

 souice from which is derived the fuel supply of arctic travel- 

 lers. The same may be said of the Youcon valley in Alaska, as it is 

 this tree that occupies the valley and islands of that river on all newly 

 formed lands, but in time gives place to spruce as the sub-soil 

 becomes cold and moist from the density of the poplar and willow 

 growth. 



