EXPLANATIONS OF THE PLATES. 

 Plate DLX. Pinus pondbbosa. 



1. An end of a branch with staminate flowers, natural size. 



2. Portion of a staminate flower, enlarged. 



3. Diagram of the involucre of the staminate flowers. 



4. An anther, front view, enlarged. 



5. An anther, side view, enlarged. 



6. An end of a branch with pistillate flowers, natural size. 



7. A pistillate flower, enlarged. 



8. A scale of a pistillate flower, under side, with its bract, enlarged. 



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



10. Tip of a leaf, enlarged. 



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



12. A seedling plant, natural size. 



Plate DLXI. Pinus ponderosa. 



1. A fruiting branch, natural size. 



2. A seed, natural size. 



3. Vertical section of a seed, enlarged. 



4. An embryo, enlarged. 



5. A cluster of leaves, natural size. 



Plate DLXII. Pinus ponderosa, var. Jeffreyi. 



1. An end of a branch with staminate flowers, natural size. 



2. Diagram of the involucre of the staminate flower. 



3. Bract of a staminate flower, enlarged. 



4. An involucre of a staminate flower, enlarged. 



5. An anther, side view, enlarged. 



6. An anther, front view, enlarged. 



7. An end of a branch with pistillate flowers, natural size. 



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. 



Plate DLXIII. Pinus ponderosa, var. Jeffreyi. 



1. A fruiting branch, natural size. 



2. A cone-scale, under side, natural size. 



3. A cone-scale, side view, natural size. 



4. A seed with its wing, natural size. 



5. A seed with its wing, natural size. 



6. A seed-wing, natural size. 



7. Vertical section of a seed, enlarged. 



8. An embryo, enlarged. 



Plate DLXIV. Pinus ponderosa, var. scopulorum. 



1. A fruiting branch, natural size. 



2. A cluster of leaves, natural size. 



3. A cluster of leaves, natural size. 



Plate DLXV. Pinus ponderosa. 



1. A fruiting branch of var. Mayriana, natural size. 



2. A fruiting branch from a tree on the Chiricahua Mountains of 



Arizona, natural size. 



3. A cone with entire base from a tree on the Chiricahua Mountains 



of Arizona, natural size. 



