26 



THE ROOT, OR DESCENDING AXIS. 



Such is the case with the mustard, beet, maple, and most of the Dico- 

 tyledonous plants. In 



123. THE INAXIAL MODE, the primary radicle, proves abortive, never 

 developing into an axial root : but, growing laterally only, it sends out 

 little shoots from its sides, which grow into long, slender roots nearly 

 equal in value, none of them* continuous with the stem. Of this nature 

 are the roots of all the grasses, the lilies and the Monocotyledons gen- 

 erally, and of the Cryptogamia. Plants raised from layers, cuttings, 

 tubers, and slips, are necessarily destitute of the axial root. 



26 



27 



FIGS. 26, Maple an axial, ramose root. 27, Parsnip a fusiform root, 

 napiform root. 29, Corallorbiza a coralline root. 



3, Turnip a 



124. THE VARIOUS FORMS OF THE ROOT are naturally and conve- 

 niently referred to these two modes of development. The principal 

 axial forms are the ramose, fusiform, napiform, conical. To all these 

 forms the general name, tap-root, is applied. 



125. THE RAMOSE is the woody tap-root of most trees and shrubs, 

 where the main root branches extensively, and is finally dissolved and 

 lost in multiplied ramifications. 



126. TUBEROUS TAP-ROOTS. In herbaceous plants the tap-root often 

 becomes thick and fleshy, with comparatively few branches. This ten- 

 dency is peculiarly marked in biennials ( 90), where the root serves as 

 a reservoir of the superabundant food which the plant accumulates 

 during its first year's growth, and keeps in store against the exhausting 

 process of fruit-bearing in its second year. Such is 



127. THE FUSIFORM (spindle-shaped) root, thick, succulent, tapering 

 downwards, and also for a short space upwards. The beet, radish, gin- 

 seng arc examples. 



