180 



TREES OF MINNESOTA. 



Plate 18. Salix nigra. Black Willow. 



1. Flowering branch of staminate tree, one-half natural size. 2. Flowering 

 branch of pistillate tree, one-half natural size. 3. Scale of staminate catkin, en- 

 larged. 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. 



