108 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



rocky slopes or cliff tops. It is useful in decorative plantings but 

 is somewhat difficult to grow. 



The sharply pointed, slender-stalked, alternate leaves (Fig. 

 97 inset), 2-4 inches long by 1-2 inches wide, are yellowish 

 green above and paler and somewhat hairy beneath. They have 

 sharply toothed margins. The showy, white, perfect flowers, 

 which appear before the leaves in early spring as erect or droop- 

 ing clusters, resemble the flowers of cherry. The fruit is a round, 

 purple, dry, insipid berry V^^-Vs inch in diameter. The thin trunk 

 bark is conspicuous because of its light gray color and scalelike 

 ridges. Serviceberry is seldom seriously damaged by diseases, 

 but it is an alternate host of some of the rusts which affect juni- 

 pers. The heavy, hard wood is of little commercial value al- 

 though it has been used in making tool handles, bows, fishing 

 rods, and lances. 



Spruce 



Although it is not native to the state, spruce is one of the 

 most common evergreens used in ornamental and windbreak 

 plantings in Illinois. It is also grown extensively for Christmas 

 trees. Norway spruce {Picea abies), white spruce (P. glauca), 

 and Colorado blue spruce (P. pungens) are excellent for wind- 

 break plantings. 



Engelmann (P. engelmanni) , blackhill (P. glauca densata), 

 Koster blue (P. pungens var. Kosteriana) , Colorado blue (Fig. 

 98), Norway, and white spruces are used extensively in orna- 

 mental plantings. Spruces are pyramidal in shape and have scaly 

 bark and branches in whorls. They grow best in deep, moist, 

 sandy loam soil, and often reach a height of 50-70 feet. 



The needles (Fig. 98 inset), usually four sided and spirally 

 arranged, persist for several years. They vary from Ys to 1 inch 

 long and from bluish green to dark green on the above species. 

 They sit on cushion-like growths which make the deeply grooved 

 twigs appear corrugated. Male and female flowers are borne 

 separately on the same tree. The yellow to red catkin-like male 

 flowers are produced in axils. The green to purple female flowers 

 are produced terminally and develop into oval to cylindrical cones 

 which are pendulous. Two small, compressed, winged seeds are 

 produced under each persistent scale. 



Spruce trees in ornamental plantings are frequently infested 

 with spruce spider mites which feed on the needles, causing many 

 needles to drop during the growing season. Spruces are suscep- 



