10 BULLETIN 316, IT. S. DEPARTMENT OF AGRICULTURE. 



On the lower ground, such as small islands, old river beds, sand 

 bars, and fills, the principal species present are black, sandbarj and 

 peachleaf willows, and cottonwood above Cairo, 111., the peachleaf 

 dropping out below that point. Above Cairo the peachleaf willow 

 divides with the black willow the position of the leading tree willow, 

 but does not quite attain the size of the black willow or grow so 

 rapidly. The black willow is prevalent along practically the whole 

 course of the Mississippi, increasing in abundance and size along the 

 lower reaches. The black willow and cottonwood are as a rule the 

 first tree species to appear on new land. 



FORM AND GROWTH OF INDIVIDUAL TREES. 



Black willow trees may be divided into two general classes — that 

 found in the North or on poor soil in the South and that of the rich 

 alluvial river bottoms of the South. The first are typically 30 to 60 

 feet high and from 6 to 18 inches in diameter. They occur in pure 

 stands over small areas or, more often, in groups of several clustered 

 stems. In the open the black willow is a short, branchy, crooked 

 tree, fit only for fuel. In close stands it has a moderately straight 

 trunk or often two or three straight branches arising near the ground. 

 The northern form, grown in close stands, can be utilized for fuel, 

 charcoal, excelsior, or pulp, and occasionally for artificial limbs, but 

 seldom develops into a desirable sawlog. The southern type is con- 

 siderably different in habit of growth in the forest. The trunks are 

 usually separate and stand quite erect. In the open the tree branches, 

 like the northern form, being different only in its larger size. The 

 forest-grown tree has a minimum clear length of 20 feet and an 

 average clear length of about 40 feet, and, as a maximum, several 

 specimens have been measured having over 80 feet of clear, straight 

 bole. The tops of these trees are small, irregular, and often broken. 

 The crowns are narrow, open, and deep. The average diameter in 

 mature stands is about 18 inches at the mouth of the Ohio and in- 

 creases to 24 inches in Mississippi and Louisiana. The largest breast- 

 high diameter measurement recorded for a forest-grown black willow 

 is 44 inches and the greatest height 140 feet. The tree with the 

 greatest height measurement, however, was not the one with the 

 greatest diameter growth. The 44-inch tree was not over 125 feet 

 high and the 140-foot tree was not over 3 feet in diameter. The 

 average height in mature stands at the mouth of the Ohio is approxi- 

 mately 85 feet; in Louisiana it ranges from 100 to 120 feet. Black 

 willow is a short-lived tree. The greatest age recorded for a sound 

 tree is 70 years; the greatest age recorded for a living but unsound 

 tree is 85 years. The average age at which stands mature is 55 years 

 and under favorable conditions may be 10 years less. 



