POPLARS. 



189 



Plate 22. Populus tremuloides. Aspen. 



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

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

 enlarged. 4. Stamen, enlarged. 5. Scale of pistillate catkin, enlarged. 6. 

 Longitudinal section of pistil. 7. Mature fruit, natural size. 8. Fruit showing 

 mode of dehiscence, natural size. 9. Seed, enlarged. 10. Longitudinal section 

 of seed, enlarged. 11. Embryo, enlarged. 12. Fruiting branch, one-half natural 



