ANGIOSPERM TREES 301 



fast growing species reaches its best development in the open or 

 in mixture with other bottom-land hardwoods in the southern 

 parts of its range, where it is of secondary commercial impor- 

 tance. The wood is hard, coarse-grained and strong, very durable 

 in contact with the soil. It is very hardy when planted as an 

 ornamental, and is widely used as such, its armed branches mak- 

 ing it a highly effective hedge tree. 



The BLACK LOCUST {Robinia) is one of a group of about twenty 

 trees and shrubs whose leaves are like those of the honey locust, 

 borne on twigs armed with short, stout thorns placed one on 

 each side of the leaf scar. Terminal buds are lacking and the 

 lateral buds are small and imbedded in the twig under the leaf 

 scar. The creamy white flowers (fig. 217) are borne in showy 

 clusters which later mature to form the brown flat pod-like fruits 

 with their hard-coated, bean shaped seeds. Black locust was 

 originally restricted in its range to central Pennsylvania south- 

 ward to northern Georgia in the Appalachian Mountains, also 

 spots in southern Illinois, Indiana, and western Arkansas, but at 

 present the tree is naturalized over most of the area east of the 

 Rockies. It is a medium-sized tree with a maximum measure- 

 ment of one hundred by three feet, and when grown on good soils 

 has a clear straight trunk. It is a very fast growing tree and during 

 its youth will average two to four feet a year height growth on 

 good soils. The wood is very hard, strong, and durable; and for 

 this reason the tree has been widely planted in the United States 

 and Europe for timber, but unfortunately it has a very serious 

 insect pest in the form of the locust borer which has led to a more 

 sparing use of black locust for forest planting in some sections. 



The Hollies 



The HOLLY {Ilex) group contains about six native species 

 which reach tree size. The leaves are alternate and simple, and 

 may be either persistent or deciduous, with smooth, small- 

 toothed, or long spiny toothed margins. Holly flowers are small 

 and greenish-white, giving rise to the characteristic red or black 

 berry-like fruit which consists of a single seed surrounded by a 

 fleshy covering. 



