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 roots 
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 ¢wberous 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. The fibrous are such as con- 
sist mostly of fibres, with scarcely 
any axis; asin Buttercups, Grass- 
es. In such cases the axis ceased 
to grow immediately after ger- 886 837 
mination, and long thread-like Fig. 336. Tuberous and fusiform 
branches supplied its place. root of Beet. 
229. The jibro-tuberous roots 4. 987. Tuberous and napiform 
« 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 does it imbibe? 
In what state is this food when imbibed ? 
218. What is said of the nature of the root? What 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* 
