102 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



varieties have been developed from the wild goose plum. The 

 heavy, hard, strong, close-grained wood is suitable for turnery. 



Poplar 



Most poplars (including cottonwoods and aspens) are large, 

 fast-growing trees that live a relatively short time. They have 

 simple, triangular to circular, usually toothed, alternately ar- 

 ranged leaves (Fig. 92 and 93 insets) on round or five-sided, 

 moderate-sized twigs. The leaves of quaking aspen and most 

 other poplars have flattened petioles (leaf stems) which allow 

 the leaves to quiver in the slightest breeze. The male and female 

 flowers are produced in catkins on separate trees before the leaves 

 appear. The fruit is a small capsule borne in necklace-like strings 

 which contain many small seeds in a cottony mass. 



Poplars native to Illinois are : quaking aspen (Populus 

 tremuloides) , large-toothed aspen {P. urundidentata) , swamp 

 Cottonwood (P. heterophyUa) , and cottonwood (P. deltoides) 

 (Fig. 92). Other poplars planted in Illinois and used to some 

 extent in landscaping and in ornamental plantings are : bolleana 



Fig. 92.— The fast-grow- 

 ing cottonwood has limited 

 use for park or specimen 

 planting. Each triangular- 

 shaped leaf (inset) is at- 

 tached to the twig by a 

 flattened stem. 



