300 



PRACTICAL BOTANY 



trees are planted, and they attain considerable height by the time 



the last of the oldest crop are harvested (see Chapter XXII). 



278. The vegetative plant. The plant has a heavy central 



taproot (Fig. 247), which extends deep into the soil. From 



the taproot there de- 

 velops an extensive 

 system of roots, some 

 reaching downward, 

 and even more out- 

 ward, into the soil, 

 in this way forming 

 an abundant root sys- 

 tem that anchors the 

 plant and distributes 

 the youngest rootlets 

 in favorable positions 

 in the soil. 



The stem is gener- 

 ally straight and the 

 branches usually rise 

 in whorls. Sometimes 

 in older trees many 

 branches have died, 

 and but one or two 

 of each whorl are left. 

 The lower branches 

 are usually longest, 

 the top ones shortest, 

 and the intermediate 

 ones grading between 

 these extremes, so that the whole tree top is often quite cone- 

 like in outline. The stem and branches are covered by a heavy 

 bark, and the roots by a bark which is usually not so thick. 

 The leaves are on the younger branches. The needle leaves are 

 most conspicuous, and at their bases and on the terminal buds 

 are the brownish scale leaves. 



FIG. 246. A white pine (Pinus Strobus) 



The stem is almost straight, the branches stand 



approximately at right angles to the stem, and the 



top is irregularly conical 



