122 



ROOTS AND UNDERGROUND STEMS 



at intervals, for twelve to twenty-four hours, then fill the 

 glass with water to within lo millimeters (a half inch, 

 nearly) or less of the netting, let the batting dry, and after 

 eight or ten hours again observe the position of the roots. 

 What would you infer from this experiment as to the affin- 

 ity of roots for water ? 



170. Taproots. — Gather a stalk 

 of cotton or any hard wood shrub, 

 and one of corn or other grain, and 

 compare them with each other and 

 with the roots of seedlings of the 

 same species. Notice the differ- 

 ence in their mode of growth. In 

 the first kind a single stout pro- 

 longation called a taproot proceeds 

 from tHte lower end of the hypo- 

 cotyl and continues the axis of 

 growth straight downwards, unless 

 turned aside by some external influ- 

 ence. A taproot may be either simple, as in the turnip, 

 radish, dandelion, and most herbs, or branched, as in 

 shrubs and trees generally. In this 

 case the main axis is called the 

 primary root, and the branches are 

 secondary ones. 



258. — Branched taproot 

 maple. 



259. — Fibrous root. 



171. Fibrous and 

 Fascicled Roots. — 



In corn and other 

 grasses the main 

 axis has become 

 aborted, or failed 



to develop, and a number of independent 

 branches spring from its stub, forming 

 260.— Fascicled and what are known as fibrous roots : or the 



tuberous or fusiform , ^ , , , . , 



(secondary) roots of base of the hypocotyl, mstead of con- 

 dahiia: a, u, buds on tinuing downward in a single axis, may 



base of the stem (after . " . . , 



Gray) Split up mto a number of smaller ones- 



