250 TREES OF MINNESOTA. 
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Plate 18. Salix nigra. Black Willow. 
1. Flowering branch of staminate tree, one-half natural size. 2. Flow- 
ering branch of pistillate tree, one-half natural size. 3. Scale of staminate 
catkin, enlarged. 4. Scale of pistillate catkin, enlarged. 5. Longitudinal 
section of ovary, enlarged. 6, Fruiung branch, one-half natural size. 7. 
Summer branch, one-half natural size, 
