38 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



TREES CONSIDERED 



Arborvitae 



In Illinois, arborvitae, or white cedar {Thuja occidentalis) , 

 (Fig. 40) is native to only a few counties in the northeastern 

 part of the state. However, it is grown throughout the state for 

 ornamental purposes. Also, it is used extensively in hedge plant- 

 ings for screening and windbreaks. It will thrive in wet, neutral 

 to alkaline soil and in partial shade. During severe winters it is 

 subject to injury, especially in the northern part of the state. In 

 some years, it is severely defoliated by bagworms, and such de- 

 foliated trees usually die. Also, it is a host of the spruce spider 

 mite. 



Arborvitae is a small tree, reaching a height of 30-60 feet, 

 with a straight or divided trunk. The short branches bend up- 

 ward to form a narrow, compact, conical head. The leading 

 branches have long-pointed leaves about 14, i^ich long while the 

 lateral branches have sharp-pointed, flattened leaves about i/a 

 inch long (Fig. 40 inset). Small, solitary, yellowish male and 

 pinkish-green female cones are produced on the tips of short 



Fig. 40. — Arborvitae is 

 a small evergreen tree 

 used for screening and or- 

 namental purposes. Inset 

 shows tip of a lateral 

 branch with flattened, '/s- 

 inch-long leaves on several 

 twigs. 



