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ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 51 



Zelkova 



Zelkova or Japanese keaki tree {Zelkova serrata) (Fig. 108), 

 introduced into the United States from Japan about 1860, is a 

 short-trunked and usually crooked-trunked tree with many up- 

 right stems which form a broad, round-topped head. It grows to 

 a height of 50-60 feet, with a branch spread of 20-35 feet. It 

 is used as a specimen tree in ornamental plantings and is hardy 

 in the southern two-thirds of Illinois, 



The sharply and coarsely toothed, oval to oblong leaves (Fig. 

 108 inset) are 1-4 inches long. The foliage turns light yellow 

 in autumn. Short-stalked male, female, and perfect flowers are 

 produced on the same tree. Male flowers are produced as clusters 

 in the axils of the lower leaves. Female and perfect flowers are 

 produced singly or in groups of a few in the axils of the upper 

 leaves. The one-seeded, fleshy fruit ripens in autumn. The 

 smooth, reddish-brown bark forms rows of small scales. The 

 tough, elastic wood is used in jinrikishas in Japan. It has no 

 commercial value in this country where the tree is used only for 

 ornamental purposes. Although Zelkova has been found suscep- 

 tible to Dutch elm disease when inoculated with the fungus, it is 

 relatively free of diseases and insect pests in the United States. 



Fig. 108.— Zelkova, 

 used as a specimen 

 tree in ornamental 

 plantings, has 

 coarsely toothed 

 leaves (inset) that 

 turn light yellow in 

 autumn. 



