26 



THE BOOT, OR DESCENDINO 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 

 i-qual 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 Crypt6gamia. Plants raised from layers, cuttings, 

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



Figs. 26, Maple — an axial, ramose root. 27, Parsnip— a fusiform root. 23, Turnip — a 

 napiform root. 29, Oorallorhiza — a coralline root. 



124. The vakious 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, taji-root, is applied. 



125. The kamose, 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- 

 di'ncy is peculiarly marked in biennials (§ 90), where the root serves aa 

 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 tusiporm (spindle-shaped) root, thick, succulent, taporing 

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

 seng are examples. 



