FORMS OF ROOTS. 



105 



ground, in proportion to the growth of the branches and 

 twigs of the stem above. The axis itself may not descend 

 to any great depth, and after a few years may be found far 

 exceeded in growth by its own branches which extend hori- 

 zontally in a better soil. The greater the growth of the root? 

 the more firm will be its hold upon the ground, and the great- 

 er its capacity for drinking in liquid nourishment for the tree. 



220. The roots of herbaceous 

 plants take a great variety of 

 forms. Some are tuberous, some 

 fibrous. The tuberous are such as 

 consist of a large axis or body, with 

 small branches ; as in the Beet, 

 Ground-nut, Spring Beauty, and 

 many other biennial plants. 



221. Ti\Q fibrous are such as con- 

 sist mostly of fibres, with scarcely 

 any axis ; as in Buttercups, Grass- 

 es. In such cases the axis ceased 

 to grow immediately after ger- 

 mination, and long thread-like ^. „„„ ^ , a ^ -^ 



' , ^ Fig. 836. Tuberous and fusiform 



branches supplied its place. root of Beet. 



222. The fihrO-tulerOUS roots ^'^- ^S^- Tuberous and napifonn 

 ^ 1 /> ,1 . root of Turnip. 



are such as have some of their 



fibres thickened and fleshy, as seen in the Peony, Dahlia, 



216. Please explain the meaning of the term axis. In what two directions 

 does it grow ? 



217. What is the twofold purpose of the root? What docs it imbibe ? 

 In what state is this food when imbibed ? 



218. What is said of the nature of the root? Wliat are its only proper 

 organs ? What is said of leaves or buds ? 



219. Describe the roots of woody plants, and their growth. 



220-222. Describe tuberous roots ; fibrous ; fibro-tuberous ; tubercular. 



5* 



