230 HOWARD E. PULLING 



J. W. TyrrelP collected this species on the north shore of Selwynn 

 lake (about 60°18'N. lat., 104°30'W. long.) only about 90 miles 

 from the edge of the Barren Lands in that latitude, and at Thei- 

 taga. lake (about 59°32'N. lat., 101°30'W. long.) which is about 

 70 miles from the edge of the Barren Lands, since they swing 

 toward the south in approaching Hudson Bay. 



Jack pine appears to be fairly plentiful in the rolling, deep- 

 soil country in the bed of Lake Agassiz and rather rare eastward 

 and northward; which may be due to the extreme shallowness of 

 the soils outside this lake bed. 



Tamarack {Larix Americana Michx; L. laricina (DuRoi) 

 Koch.) is, in its root habit,, essentially like black spruce and like 

 the spruce does not appear to vary the habit with changes in the 

 depth of the soil. The tree from which the figure was taken was 

 growing on the hill near the Grand Rapids portage on the Nelson 

 river, in deep, thawed soil; it was about 8 years old and is almost 

 completely figured. It grows in low reg ons with frozen soil a 

 few centimeters below the surface, as does the black spruce. 

 Similarly it is a very northern tree, J. W. TyrrelP encountered 

 frequent individuals along the Telzoa river as far as Doobaunt 

 lake (about 63°N. lat., 102° W. long.), which is over 100 miles 

 within the Barren Lands. 



Canoe Birch {Betula papyrifera Marsh; B. alba L.) is appar- 

 ently another shallow rooted plant. The one figured was found 

 on the shore of Witchai lake (about 55°54'N. lat., 96°50' W. long.) 

 in fairly deep soil with the frost line nearly two meters below the 

 surface. This figure only shows the small terminal roots on a 

 few of the root branches and only two of the main roots are 

 shown, the others being similar; few in number, long and little 

 branched. The tree was about 25 years old. Characteristically 

 the roots are almost bare of small roots except near their tips. 

 It is also a tree of the far north : J. W. Tyrrell^ encountered it up 

 to the edge of the Barren Lands. Trees large enough for canoes 

 were found at the north end of Selwynn lake, mentioned above. 



White Spruce (Picea Canadensis (Mill.) BSP; P. alba Link.) 

 has apparently a more flexible root habit. The plant figured as 



* Tyrrell, J. B., loc. cit. 



