ILLINOIS TREES: SELECTION, PLANTING, AND CARE 



103 



(P. alba var. pijramidalis), Carolina (P. x caymdensis var. eu- 

 genei), Lombardy (P. nigra var. ifalica), and white poplar (P. 

 alba). Lombardy (Fig. 93) and bolleana poplars are upright 

 forms, with ascending branches, that may grow to a height of 

 100 feet. They are used to some extent as specimen trees, as 

 border plantings to serve as a screen, or in other situations where 

 rapid growth is desired. Most other species of poplar have nar- 

 row to broad, open, round-topped crowns. White and Carolina 

 poplar, aspen, and cottonwood are used in parks and for speci- 

 men trees. While most of these poplars will grow on a variety 

 of sites, swamp cottonwood prefers swampy ground. 



Poplars are frequently attacked by borers and canker dis- 

 eases and should be used sparingly in ornamental plantings. 

 Lombardy poplars are frequently killed by borers or Cytospora 

 canker by the time they are 10-15 years old (Fig. 9). The wood 

 of poplars is light, close grained, soft, and weak, and is of less 

 commercial value than the wood of many other trees. It is used 

 for pulp, baskets, boxes, crates, excelsior, and to some extent for 

 lumber. 



Fig. 93. — Lombardy pop- 

 lar is a tall, slender, fast- 

 growing tree used for 

 screening and accent pur- 

 poses. The leaves (inset) 

 are broader than long. 



