CHAPTER XV 



THE BOOT 



' fT^HE stalk or trunk is the upward-growing part 

 X of the plant, and needs air and light. The root, 

 on the contrary, is the downward-growing part, and 

 it needs soil and darkness. The extreme ends of 

 the root's various subdivisions are always growing, 

 always young, of delicate structure, and for that 

 reason admirably fitted for imbibing, very much 

 as a fine sponge would do, the liquids with which the 

 soil is impregnated. Because of their facility in 

 absorbing moisture these ever-growing tip-ends are 

 called spongioles. The spongioles terminate the 

 rootlets, that is to say the final subdivisions of the 

 root, subdivisions known as root-hairs on account 

 of their resemblance to real hair. 



"The root takes various forms, which are all re- 

 ducible to two fundamental types. Sometimes it 

 consists of a main body or tap-root, which sends out 

 branches as it bores deeper into the soil. This des- 

 ignation, tap-root, is a common and familiar term. 

 Sometimes the root assumes the form of a tuft, a 

 bunch of rootlets, simple or branching, which, spring- 

 ing from the same point, continue to grow at a nearly 

 equal rate and on an equal footing as to importance. 



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