THEIR RUGGED TRUNKS 



gray bark which becomes darker and on old trees 

 fissured. 



The deciduous Oaks according to their bark fall 

 into two groups. Many of the White Oaks (Quer- 

 cus alba, Q. macrocarpa, Q. bicolor, Q. stellata) have 

 light gray bark which becomes fissured with age. 

 Others like the European Oak (Quercus robur), and 

 the Red, Black, and Chestnut Oaks of America have 

 dark gray bark, varying from nearly smooth to 

 deeply fissured according to the species. The Chest- 

 nut also has dark gray, deeply fissured bark. In 

 the Sweet Birch the bark is smooth and almost 

 black, and in the Cherries lustrous, chestnut-brown, 

 and peeling. In the Plane and certain Hickories the 

 bark flakes off in plates or strips leaving smooth 

 white or pale brown scars; in Stuartia and the 

 Crepe Myrtle (Lagerstroemia) this is carried to the 

 extreme and the trunks become smooth and polished. 

 The Robinia has a grayish, deeply fissured, fibrous 

 bark, and that of the Elm, Linden, and many other 

 common trees, is dark and irregularly fissured. In 

 the American Honey-locust (Gleditsia triacanthos) 

 the bark is almost black, cracked and fissured, 

 whereas that of its Chinese relative {G. macracantha) 

 is quite smooth and pale gray. A similar difference 

 obtains between the Kentucky CofTee-tree and its 

 Chinese congener. In the former the bark is dark, 

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