May, 1921.] 



The Canadian Field-Naturalist. 



85 



Douglas and Grand Firs are the only two 

 trees which I have had the opportunity of 

 studying. The characteristic seems to ob- 

 tain in all conifers where root union has 

 taken place. Doubtless it would not occur 

 in conifers which possess the power of 

 stump sprouting, such as tjie California 

 Redwood {Sequoia senipervirens, (Lamb) 

 Endlicher). The Bigtree {Sequoia ivasJi- 

 ingioniama (Winsl.) Sudworth), on the 



other hand, cannot sprout but shows the 

 overgrowth characteristic in a very marked 

 degree. 



The question of the frequency of natural 

 graftage as well as the extent to which it 

 takes place among the trees in a forest is 

 necessarily pertinent to the consideration 

 of t,he question of overgrowth. Inarching 

 of roots of a single tree is a well-known 

 phenomenon. Whether wholesale inter- 



"*&& 



Fig. 3: Douglas Fir. Partial overgrowth of stump (to the right) due to natural graft 

 of its roots with those of a foster Douglas fir (to the left) The graft ha& 

 developed into a bar of wood connecting the tree and stump. The ring of 

 annual increment of the living tree on the left is seen to be enveloping the 

 stump on the right. The centre of the stump, not being preserved by resin, is 

 decaying and would have become one of the hollow stump types in which there 

 is a rim of live wood only. Locality, Sylvan Lane, Gonzales Hill, Victoria, B. C- 



