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TEXTBOOK OF BOTANY 



Table 11. Maximum Sizes and Ages Attained by Certain Trees 



Name of Tree 



Location 



Western yellow pine 



Sugar pine 



Douglas fir 



Redwood 



Big tree (sequoia) 



Big cypress of Tule 



Western juniper 



Norway maple 



Sugar maple 



Bur oak 



Tulip 



Sycamore 



Black walnut 



Western N. A. 

 California 

 British Columbia 

 California 

 California 

 Oaxaca, ^Mexico 

 California 

 Europe 



Wabash Valley 

 Wabash ^'alley 

 Wabash Valley 

 Southern Indiana 

 Wabash Vallev 



placed in an environment in which the terminal vegetative bud will 

 become a flower bud. Similarly, artificial cultures of root tips, described 

 in Chapter XXI, indicate that the apical meristem of a root tip has 

 potentialities of unlimited growth if it is repeatedly removed from the 

 remainder of the root svstem and kept in a suitable environment. What 

 then are the factors that limit the growth in length of stems and roots 

 when thev are attached to the whole plant? 



Processes in stems. All the processes characteristic of a vegetative cell 

 occur in the cells of stems. In addition, there are certain processes that 

 occur in some vegetative cells but not in others. Photosynthesis does not 

 occur in all vegetative cells, but such processes as respiration, digestion, 

 and assimilation do. On the other hand, photosynthesis occurs in any 

 cell of a leaf, or a stem, or a root that contains chlorophyll and is 

 exposed to a suitable environment. But many leaves and stems do not 

 contain chlorophyll. All we can say is that in most ferns and seed plants 

 photosynthesis occurs more abundantly in leaves than in stems and roots. 



When all kinds of leaves, stems, and roots are compared, there are very 

 few processes that can be said to be distinctly characteristic of any 

 one of these three types of vegetative organs. Perhaps there is no process 

 that occurs in all stems that does not occur in some roots or some leaves. 

 There are very few species of plants which have leaves that bear other 

 leaves; roots may never bear leaves, but there are also certain kinds of 

 stems that do not bear leaves. Flowers do not develop directly from 

 leaves or from roots; neither do they develop on all types of stems. When 

 water and salts move from the soil to the leaves of a dandelion plant, the 



