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TEXTBOOK OF BOTANY 



and the ground hemlock, are not at all cone-like, but the other 

 characteristics of these plants show that they are related to the 

 cone-bearing forms. Most of the conifers are trees. A few 

 are low shrubs, like the ground hemlock, or even creeping 

 forms, like the creeping juniper. Other conifers are the 



spruces ; the firs ; the larches 

 (one of which is the American 

 tamarack) , whose foliage 

 leaves, differently from those 

 of most conifers, live for only 

 one season and are shed in 

 the fall ; the arbor vitas, or 

 white cedar ; the hemlocks ; 

 the giant redwood of Cali- 

 fornia, which reaches a 

 greater size than that of any 

 other living plant excepting 

 some Australian gumtrees ; 

 and the bald cypress of the 

 southern United States, re- 

 markable for its " knees," 

 vertical outgrowths of the 

 roots which rise several feet 

 above the surface of the 

 ground and which seem to 

 be respiring organs. Many 

 of these other conifers, like 

 the pines, are valuable as 

 timber trees and as sources 

 of resin and of various special products such as Canada 

 balsam and spruce gum. The spruce is the most impor- 

 tant source of pulp for paper-making ; but as it is becom- 

 ing scarcer, the wood of some other trees, especially that of the 

 balsam fir, is being used for this purpose. Attempts are 

 being made also to find ways of using pxilp obtained from 



Fig. 78. — White spruce trees. 

 Photograph by L. S. Cheney. 



