12 BULLETIN 316, U. S. DEPARTMENT OP AGRICULTURE. 



Table 1. — Average height of willow stands in the Mississippi Valley. 



Stand near — 



Stand. 



Soil. 



Average 

 height. 



Clay City, Ind 



Ste. Genevieve, Mo 



Cairo, 111 



Memphis, Term 



Helena, Ark 



Vicksburg, Miss 



St. Joseph, La 



Williamsport, La... 



Years. 

 53 

 40 

 42 

 37 

 55 

 41 

 45 

 57 



Close 



Medium. . . 



Close 



Medium... 



Close 



...do , 



...do 



...do 



Sandy 



do 



do 



Verv poor drainage. 



Black 



do 



do 



do 



Feet. 



82 

 74 

 83 

 81 

 110 

 98 

 116 

 104 



In the South black willow attains its principal height growth at 

 from 35 to 40 years; in the North at from 30 to 35 years. In the 

 South, however, growth frequently continues more slowly after this 

 age until the heights ranging between 100 and 135 feet are reached. 

 Table 2 gives the average height growth of black willow, based on 

 255 trees in the Mississippi Valley region from southern Indiana and 

 southern Missouri to central Louisiana. Most of these measurements 

 were taken in the southern half of this range. 



Table 2. — Height growth of black willow in the Mississippi Valley. 



(Based on 255 trees.) 







Growth 



Periodic 







Growth 



Periodic 



Age. 



Height. 



in 5-year 



annual 



Age. 



Height. 



in 5-year 



annual 







periods. 



growth. 







periods. 



growth. 



Years. 



Feet. 



Feet. 



Feet. 



Years. 



Feet. 



Feet. 



Feet. 



5 



32 



32 



6.4 



35 



96 



7 



1.4 



10 



50 



18 



3.6 



40 



101 



5 



1.0 



15 



83 



13 



2.6 



45 



105 



4 



.8 



20 



73 



10 



2.0 



50 



109 



4 



.8 



25 



82 



9 



1.8 



55 



113 



4 



.8 



30 



89 



7 



1.4 



60 



116 



3 



.6 



DIAMETER GROWTH. 



Black willow makes its most rapid diameter growth during the 

 first 10 years, after which the growth falls off gradually. At the age 

 of 60 years the average tree is generally mature or overmature, and 

 produces little increment after that. Occasionally an individual will 

 survive longer than this in a protected place and continue growing 

 up to an age of 75 years. On poor sites, such as a rather sandy 

 river bank, or on soils having a scant moisture supply, the diameter 

 growth is about 0.4 of an inch per year for the first 10 years, while 

 on the best sites in the South, where there is a long growing season, 

 it averages from 0.5 to 0.7 of an inch. The maximum annual diame- 

 ter growth on the best sites is 0.9 of an inch the first 10 years. A 

 particularly interesting fact is noted in that beyond the age of 45 

 years the annual diameter growth of all trees is practically the same, 

 averaging about 0.28 of an inch. The trees having a maximum 



