120 TREES OF NORTH AMERICA 



Japan in the Old World. Of the thirty-four species now generally recognized fifteen are 

 found in North America. The wood of many of the American species is employed in large 

 quantities for paper-making, and several species furnish wood used in construction and in 

 the manufacture of small articles of woodenware. The bark contains tannic acid and is 

 used in tanning leather and occasionally as a tonic, and the fragrant balsam contained in 

 the buds of some species is occasionally used in medicine. The rapidity of their growth, 

 their hardiness and the ease with which they can be propagated by cuttings, make many of 

 the species useful as ornamental trees or in wind-breaks, although planted trees often suffer 

 severely from the attacks of insects boring into the trunks and branches. Of the exotic 

 species, the Abele, or White Poplar, Populus alba L., of Europe and western Asia, and its 

 fastigiate form, and the so-called Lombardy Poplar, a tree of pyramidal habit and a form 

 of the European and Asiatic Populus nigra L., and one of its hybrids, have been largely 

 planted in the United States. . 



Populus, of obscure derivation, is the classical name of the Poplar. 



CONSPECTUS OF THE NORTH AMERICAN SPECIES. 



Stigmas 2, 2-lobed, their lobes filiform; leaf stalks elongated, laterally compressed; buds 



slightly resinous. 



Leaves finely serrate; winter-buds glabrous. 1. P. tremuloides (A, B, F, G). 



Leaves coarsely serrate; winter-buds tomentose or pubescent. 2. P. grandidentata. 

 Stigmas 2-4, 2-lobed and dilated, their lobes variously divided; buds resinous. 

 Leaf-stalks round. 



Leaves tomentose below early in the season, broadly ovate, acute or rounded at apex. 



3. P. heterophylla (A, C). 

 Leaves glabrous or pilose below. 



Leaves dark green above, pale, rarely pilose below. 



Ovary and capsule glabrous. 4. P. tacamahacca (A, B, F). 



Ovary and capsule tomentose or pubescent. 5. P. trichocarpa (B, F). 



Leaves light green on both surfaces, glabrous. 



Leaves lanceolate to ovate-lanceolate. 6. P. angustifolia (F). 



Leaves rhombic-lanceolate to ovate. 7. P. acuminata (F). 



Leaf-stalks laterally compressed. 



Leaves without glands at apex of the petiole, coarsely serrate, thick. 

 Pedicels shorter than the fruit. 

 Disk cup-shaped. 



Branchlets stout; capsule '-' long. 8. P. Fremontii (G, H). 



Branchlets slender; capsule not more than \' long. 9. P. arizonica (F, H). 

 Disk minute. 



Branchlets glabrous; leaves broad-ovate to deltoid, long-pointed and acum- 

 inate at apex. 10. P. texana (C). 

 Branchlets pubescent; leaves broad-ovate, abruptly short-pointed 'or acute at 

 apex. 11. P. McDougallii (G, H). 

 Pedicels 2 or 3 times longer than the fruit; leaves broadly deltoid, abruptly short- 

 pointed. 12. P. Wislizenii (E, F). 

 Leaves furnished with glands at apex of the petiole. 

 Branchlets stout; leaves thick. 



Winter-buds puberulous; leaves coarsely serrate; branchlets light yellow. 



13. P. Sargentii (F). 



Winter-buds glabrous; leaves less coarsely serrate; branchlets gray or reddish 



brown. 14. P. balsamifera (A, C). 



Branchlets slender; leaves thin, ovate, cuneate or rounded at base, finely serrate. 



15. P. Palmeri (E). 



