ILLINOIS TREES: SELECTION. PLANTING, AND CARE 45 



male catkins start forming in autumn while the green female 

 catkins do not form until spring. The erect, conelike fruit, 

 ■U-IV2 inches long, contains oval nutlets which appear rounded 

 because of lateral wings. 



Some birches are relatively small trees, growing to a height 

 of 30-50 feet (European birch), while other birches reach a 

 height of 60-70 feet (cherry birch). Also, the birches with pen- 

 dulous branches are graceful in appearance (Fig. 46). Birch 

 trees are attractive to birds. 



Birches growing on dry sites and in soil low in fertility are 

 frequently attacked by the bronze birch borer. Extensive borer 

 damage results in death of infested trees. Also, such weakened 

 trees are susceptible to Melanconium canker, a fungus disease. 

 In wet seasons the leaves may be affected by such fungus 

 diseases as powdery mildew and leaf spot. The hard, close-grained 

 wood of birch, is strong and is used for agricultural implements, 

 furniture, dowels, toothpicks, and numerous other articles, espe- 

 cially novelties. The wood of cherry and yellow birch is heavy 

 while the wood of river, canoe, and gray birch is light. 



Black Locust 



This moderate-sized tree {Robinia pseudoacacia) , also called 

 common or yellow locust and false acacia, grows to a height of 

 40-60 feet, with a branch spread of 20-35 feet (Fig. 47). Al- 

 though it prefers an alkaline soil, it grows on a wide variety of 

 soils throughout Illinois. It is frequently used as soil cover to 

 overcome erosion and to reclaim spoil banks and other types of 

 poor soil. It is not used extensively in ornamental plantings 

 because it produces numerous sprouts from roots and is subject 

 to severe damage by the locust borer, ice, and wind. 



Black locust produces conspicuous, fragrant, nectar-bearing, 

 perfect white flowers in large pendant clusters which attract 

 insects and birds in the spring. It also produces thin, flat, bright 

 reddish-brown seed pods 3-4 inches long which may be trouble- 

 some in lawns. Each seed pod contains 4-8 orange-brown, kidney- 

 shaped, hard seeds approximately 1/4 inch long. The large alter- 

 nate leaves (Fig. 47 inset), which measure 6-10 inches long, are 

 made up of 7-19 smooth, oval leaflets, 1^ 2-2 inches long and dark 

 green above but pale beneath. The scaly, reddish-brown bark is 

 divided into interlacing, fibrous ridges by deep furrows. The 

 heavy, hard, yellowish-brown wood is very durable and is used 

 for fence posts, railroad ties, and many other purposes. 



