86 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



feet. The smooth, alternate leaves (Fig. 79 inset) are divided al- 

 most halfway to the midribs into 7-11 lobes, and usually each 

 lobe has three smaller, bristle-tipped lobes. The leaves are dull 

 green above, yellow-green below, and from 5 to 9 inches long and 

 4 to 6 inches wide. The 4- to 5-inch-long male catkins and the 

 short, hairy female spikes are borne separately on the same tree. 

 The female flowers are borne in the axils of the new leaves. The 

 1-inch-long, oblong acorn is somewhat hairy at the cup end. The 

 bitter-kernelled nut is one-fourth to one-third enclosed by a 

 saucer-shaped cup. The trunk bark is dark brown and is fissured 

 into low, continuous, flat-topped ridges. Red oak is one of the 

 faster-growing oaks. It is resistant to injury by ice and wind and 

 is relatively easy to transplant. It is useful as a specimen or lawn 

 tree and in large gardens and wide parkways. 



White oak (Fig. 80) is a large tree with stout branches that 

 are resistant to injury by ice and wind. It grows to a height of 

 80-100 feet. The smooth, alternate leaves (Fig. 80 inset), bright 

 green above and pale green below, are shallow to deeply lobed, 

 with seven to nine lobes. They are 5-9 inches long and 2-4 inches 

 wide. The young unfolding leaves are soft silver-gray to red and 

 hairy below. The 2\-)- to 3-inch-long, hairy male catkins and the 

 short, bright red, inconspicuous female spikes are produced sep- 

 arately on the same tree, the female spikes being produced at the 

 base of the new leaves. The shiny, light brown, oval, %.-inch- 

 long acorns are one-fourth enclosed in shallow cups covered with 

 warty scales. The cups are attached to 1- to 2-inch-long stalks or 

 directly to the twigs. The trunk bark is light gray to nearly 

 white and is divided by shallow fissures into long, irregular, thin 

 scales. White oak is difficult to transplant and grows very slowly. 

 However, it is an excellent shade tree and is prized in ornamental 

 plantings. 



Bur oak (Fig. 81) is a moderately large tree with a broad 

 crown of massive, spreading branches that are resistant to injury 

 by ice and wind. It usually grows to a height of 60-70 feet but 

 may approach 100 feet. It thrives throughout the state, growing 

 in the sands of the north, in the gravelly moraines of the central 

 part, and in the bottomlands of the north and south. It has thick, 

 lustrous, five- to seven-lobed, alternate leaves (Fig. 81 inset) 

 that are 6-12 inches long and 3-6 inches wide. The leaves expand 

 from a wedge-shaped base to a very large and wavy-toothed end 

 lobe. They are deep green above and pale green and hairy be- 

 neath. The 4- to 6-inch-long, white-wooly male catkins and the 



