154 TREES OF NORTH .\3IERICA 



Leaves deltoid or broadly ovate, usually abruptly acuiniiiate, coarsely creuately 



serrate. D. P. deltoidea (A, C, F). 



Leaves deltoid or reniform, usually short-pointed at the apex, coarsely and irreg-u- 



larly creuately serrate. 10. P. Fremoutii (F, G). 



Pistillate flowers on long- slender pedicels. 



Leaves deltoid, abruptly short-pointed, coarsely creuately serrate. 



11. P. Wislizeni (E, H). 



1. Stiffmas 2 ^ capsule 2-valved- leaf -stalks compressed laterally- buds slightly resinous. 



1. Populus tremuloides, Michx. Aspen. Quaking Asp. 



Leaves ovate or semiorbicular, abruptly narrowed at the apex into short broad 

 points, regularly serrate, with small incurved callous glandular teeth, except at the 

 broad slightly cordate truncate or rarely wedged-shaped base, thin and firm, dark 

 green and lustrous above, pale dull yellow-green below, l|'-2' long and broad, with 

 slender veins forked and united near the margins and reticulate veinlets; their peti- 



oles slender, compressed laterally, l^'-3' long. Flowers : aments l|'-2^' long, the 

 pistillate becoming 4' long at maturity, their scales deeply divided into 3-5 linear 

 acute lobes fringed with long soft gray hairs; disk oblique, the staminate entire, the 

 pistillate slightly crenate; stamens 6-12; ovary conical, with a short thick style and 

 erect stigmas thickened and club-shaped below and divided into linear diverging 

 lobes. Fruit maturing in May and June, oblong-conical, light green, thin-walled, 

 nearly i' long; seeds obovate, light brown, about -^^ long. 



A tree, often 100 high, with a trunk occasionally 3 but generally not more than 

 18'-20' in diameter, slender remote and often contorted branches somewhat pen- 

 dulous toward the ends, forming a narrow symmetrical roundrtopped head, and 

 slender branchlets covered with scattered oblong orange-colored lenticels, bright 

 red-brown and very lustrous during their first season, gradually turning light gray 

 tinged with red, ultimately dark gray, and much roughened for two or three years 

 by the elevated leaf-scars. Winter-buds slightly resinous, conical, acute, often 

 incurved, about ^' long, narrower than the more obtuse flower-buds, with 6 or 7 

 lustrous glabrous red-brown scales scarious on the margins. Bark thin, pale yellow- 



