UNIVERSITY OF WISCONSIN 
COLLEGE OF AGRICULTURE 
 
DEPARTMENT OF WILDLIFE MANA13EMENT 
Mr. David B. Cook 
State Conservation 
Albany 7, New York 
 
424 UNIVERSITY FARM PLACE 
MADISON S, WISCONSIN 
March s, 1945 
 
Department 
 
Dear Dave: 
I have watched lots of jackpines and am inclined to think 
that Kaufman's growth period may not be too long for certain 
particular4years. Jackipine buds certainly begin to elongate 
before any other species, my own records showing April 25 
for both 1944 and 1943. If '42 was an early year, Kaufman's 
April 1 would be not impossible. 
In certain years, jackpine in this region grows twice and 
this may account for the 101 days. 
I don't know the present group at Cloquet, but I would 
welcome their participation in the red pine phonology. I 
happen to have a rush season, and wonder if you could take 
it up with them. If not convenient for you to do so, 
let me know, and I will do my best. 
Yours sincerely, 
 
Aldo Leopold