330 APPENDIX E 



Picea mariana (Mill.) B. S. P. 



The black spruce does not attain the size of the white spruce. 

 It is more a tree of the muskegs, but has the same general dis- 

 tribution. 



Populus tremuloides Michx. 



The quaking aspen is common throughout the region to near 

 the tree limit. We noted that its leaves were still green near 

 Caribou Island, Great Slave Lake, on September 23. 



Populus balsamifera Linn. 



The balsam poplar attains a large size on the lower Athabaska 

 and the Slave at least 100 feet high. We observed it as far as 

 the eastern extremity of Great Slave Lake, but there it is scarcely 

 more than a shrub. Its leaves had partially turned color, near 

 Caribou Island, on September 23. 



* Salix arctica Pall. Last woods, east shore, Artillery Lake, 



August 6. 



* Salix alaxensis (And.) Cov. Caribou Island, Great Slave 



Lake, July 21. 



This is a widely spread species in the north, with decidedly 

 woolly leaves and twigs. 



* Salix atra Rydb. Caribou Island, Great Slave Lake, July 21. 



* Salix Candida Fleugge. Near Stone Island, 20 miles north of 



Fort Resolution, Great Slave Lake, July 17. 



* Salix chlorophylla And. Near Stone Island, 20 miles north 



of Fort Resolution, Great Slave Lake, July 17. 

 A medium-sized willow with dark red twigs. 



* Salix myrtillifolia And. Caribou Island, Great Slave Lake, 



July 21. 



A species of Arctic and subarctic distribution, and especially 

 abundant just south of the tree limit. 



