44 



Elementary Work in Botany. 



Weak stems, whether herbaceous or woody, may creep, 

 trail, run, twine, or climb. Bermuda grass and other plants 

 rooting at the joints are creepers. A strawberry has run- 

 ners. Morning-glories and some beans are twiners. Get 

 roots like beets or radishes for the next work. 



EXERCISE 20. 



Roots and Their Work. Roots grow out of stems. 

 Seedlings, as you have learned, have roots which grow from 

 the caulicle or stem of the embryo. At first there is a 

 single root which is apparently but a continuation of the 

 stem. From this grow secondary roots. If the central 



root continues to be much larger 

 than the others it is called a tap 

 root (a in Fig. 29). Many plants 

 have fibrous roots, as shown at b 

 in Fig. 29 and on p. 50, 51. Plants 

 of the lily family, the cultivated 

 ,-\K i )]\ \ \ > grains, and all grasses have fibrous 

 roots. Often starch and sugar are 

 stored in roots instead of in bulbs, 

 etc. When tap roots are thus dis- 

 tended they become spindle-shaped, 

 as are carrots, or napiform, which 

 is the shape of a turnip. Secondary roots, like those of 

 sweet-potato and dahlia, may be in clusters or bunches 

 called fascicles. The underground system of roots, root- 

 lets, and root hairs corresponds to the stems, branches, 



Fig. 2"). Roots, a. Tap root. b. 

 Fibrous roots. 



