ROOTS. 95 



generally. It must be mentioned here, also, that there are 

 some exceptions to the general statement that roots do 

 not produce buds. It is well known that new stems are 

 sent up by the roots of Poplars and of Apple trees, for 

 example, especially if the roots have been injured. These 

 oases must be regarded as abnormal. 



132 You will remember that in our examination of 

 some common seeds, such as those of the 

 Pumpkin and Bean (Figs. 7 7-81), we found 

 at the junction of the cotyledons a small 

 pointed projection called the radicle. Now, 

 when such a seed is put into the ground, 

 under favorable circumstances of warmth 

 ind moisture, it begins to grow or germi- 

 nate, and the radicle, which in reality is a 

 minute stem, not only lengthens, in most 

 Fig. "122. cases, so as to push the cotyledons 

 upwards, but developes a root from its lower 

 extremity. All seeds, in short, when they 

 germinate, produce roots from the extremity 

 of the radicle, and in a direct line with it, and 

 roots so produced are called primary roots. In 

 Monocotyledons the primary root is but very 

 slightly developed, the fibrous roots character- 

 istic of these plants bursting forth from the 

 sides of the radicle at an early period of growth. 

 In other plants the primary root either assumes Fig. 123. 

 the form of a distinct central axis larger than any of its 

 branches, and called a tap-root (Fig. 123), examples of 

 which are furnished by the Mallow, the Carrot, and the 



Fig. 122. Magnified tip of Hyacinth root ; a, the root-cap. (Hooker.) 

 Fig. 123. Tap-root of Dandelion, 



