THE PROBLEM OF FOOD AIOVEMENT IN TREES. 

 By S. B. Elliott. 



The old theory regarding tissues in which food materials move, 

 namely, the sieve tubes of the bast, would appear faulty when 

 we have to deal with girdled trees. There are examples of 

 trees completely girdled which nevertheless continue to live and 

 grow for years, showing that food materials must descend with- 

 out the bark and bast, and food materials and water must ascend 

 in sufficient amounts in the older portions of the wood. It is 

 also interesting to note that this takes place in conifers, which 

 are without tracheal tubes, the latter being known to assist in 

 food movement of broadleaf trees. 



We can add one good illustration to the collection of evidence. 

 A young White pine girdled about 18 inches above the ground 

 by some rodent (the teeth marks being visible) by which bark, 

 cambium, and some sapwood had been removed supported three 

 whorls of branches above the girdle, but had no leader nor 

 branches below the girdle. No bark had formed on the girdled 

 part. The diameter below the girdle is 2.2 inches, at the girdle 

 2.1 inches, at 6 inches above girdle 3.9 inches, halfway between 

 first and second whorls 3.8 inches and halfway between second 

 and third whorls 2.2 inches. A counting of rings shows 13 

 (possibly 14) above and 8 at and below the girdle, showing that 

 the tree had lived at least 5 years after being girdled without 

 supplying food to the roots except what could have passed out- 

 side of bast tissues through old wood.* (See frontispiece.) 



Some of the questions raised by the conditions given in the 

 above description are: First, Why did not the tree die when so 

 severely girdled; second, since it continued to live, why did the 

 lower portion between root and girdle not continue to grow ; and, 

 third, why has that part between second and third whorls of 

 limbs made so little growth each year as to appear, by diameter 

 measurement, to have remained stationary? 



*An account of a similar case is found in the U. S. Forestry Division 

 Bulletin 22 : The White Pine. 



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