250 



TREES OF MINNESOTA. 



Plate 18. Salix nigra. Black Willow. 



i. 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. Fruiting 'branch, one-half* natural size. 7. 

 Summer branch, one-half natural size. 



