100 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



Fig. 90. — Limber pine 

 becomes broad and 

 round topped with ag^e. 

 The twisted needles 

 (right inset) are in 

 bundles of five. Nu- 

 merous needles on a 

 shoot tip are shown in 

 the left inset. 



less long, have thick shells. The bark, which is gray and smooth 

 when young, becomes dark brown and deeply fissured with age. 

 Limber pine is used occasionally in ornamental plantings. It 

 is relatively free of diseases and insect pests. The soft, light, 

 close-grained wood is clear yellow but turns red when exposed 

 to air. It is used occasionally for lumber. 



Plum 



Two plums, wild plum (Prunus americana) and wild goose 

 plum (P. hortulana) , are native to Illinois. These and several 

 introduced species and selections are used in ornamental plant- 

 ings because of their showy flowers and conspicuous fruits, or 

 sometimes, as in the case of the purple-leaf plum, because of their 

 foliage color. 



Wild plum (Fig. 91), with its broad head formed from many 

 spreading, upright branches, is common throughout the state. 

 It grows on various types of soils and reaches a height of 20-30 

 feet, with a branch spread of 10 feet. The long-pointed, egg- 

 shaped, firm, alternate leaves (Fig. 91 inset), 21/2-4 inches long 

 and 11/2 inches wide, have sharply toothed margins and are dark 



