EXPLANATION OF THE PLATES. 



Plate DXCL Plntjs heterophylla. 



1. A cluster of staminate flowers, natural size. 



2. Diagram of the involucre of the staminate flower. 



3. An involucre of a staminate flower, enlarged. 



4. An anther, front view, enlarged. 



5. An anther, side view, enlarged. 



6. A branch with pistillate flowers and yearling cones, natural size. 



7. A pistillate flower, enlarged. 



8. A scale of a pistillate flower, upper side, with its ovules, enlarged. 



9. A scale of a pistillate flower, lower side, with its bract, enlarged. 



10. Tip of a leaf, enlarged. 



11. Cross section of a leaf, magnified fifteen diameters. 



12. Winter branch-buds, natural size. 



Plate DXCII. Pinus heterophvlla. 



1. A fruiting branch, natural size. 



2. A cone-scale, upper side, with its seeds, natural size. 



3. A seed, natural size. 



4. Vertical section of a seed, enlarged. 



5. An embryo, enlarged. 



