170 



The Poplars 



with a trunk 2 meters thick. The tree has often been regarded as a variety of the 



Balsam poplar, P. balsamijera Linnaeus. 



The old bark is thick, gray, and ridged. The young twigs are stout, round, 



slightly hairy, becoming smooth and shining. The buds are sticky, resinous, 



narrow, pointed, 2.5 cm. long or less. The leaves are broadly ovate, pointed, 



heart-shaped, or trun- 

 cate at the base, 6 to 15 

 cm. long, 3 to 12 cm. 

 wide, dark green above, 

 pale green beneath, 

 bluntly and rather 

 evenly toothed, quite 

 hairy when young, the 

 upper surface smooth at 

 maturity, the under side 

 usually more or less 

 hairy on the veins; the 

 leaf-stalks are round 

 and hairy or hairy- 

 fringed. The tree 

 flowers in April or May; 

 the catkins are 12 cm. 

 long, or less, their scales 

 cut into many narrow 

 sharp lobes, the stami- 

 nate ones densely 

 flowered. The ripe pis- 

 tillate catkins are often 



Fig. 125. — Balm of Gilead. 



15 cm. long; the capsules are short-stalked, narrowly ovoid, pointed, smooth, 6 

 to 8 mm. long. 



It is a fast-growing tree, the lower branches widely spreading, and it is desirable 

 for plE&iting where rapid effect is wanted. Its wood closely resembles that of the 

 Balsam poplar, but is shghtly heavier, its specific gravity being about 0.39. The 

 western form has been described by Dode as a distinct species, P- hastata. 



5. RYDBERG'S COTTONWOOD — Popnlus acuminata Rydberg 



Popvlus coloradensis Dode 



This species has been confused with the Narrow-leaved cottonwood, which it 

 somewhat resembles. It inhabits the borders of streams and lakes from South 

 Dakota to Assiniboia, western Nebraska, New Mexico, Utah, and Nevada, attain- 

 ing a maximum height of about 20 meters and a trunk diameter of about 4.5 

 meters. The lower branches spread widely, the upper are nearly erect. 



