38 



THE ROOT. 



Rhizoma root. 



Fig. 36. 



(1.) The Rhizoma or Roolstock grows in nearly a horizon- 

 tal direction, emitting roots 

 from its under Bide, increas- 

 ing by one extremity only, 



at which it ]>nts forth leaves 

 and flower-stems, and gradu- 

 ally dying at the other. Its 

 suit ace is generally marked 

 by irregular ridges formed by 

 the bases of decayed leave?. 

 The Calamus, Iris, Lily, and 

 some of the grasses afford 

 good examples of this variety, 

 Fig. 35. The scaly roots come under 

 the same variety, as is exhibited in the 

 Hydrophyllum canadense. 



*(2.) The Cormus (Fig. 36) is that vari- 

 ety which increases beneath the earth 

 by the development of buds in the axils 

 of the scales, but retains its globular 

 figure, and propagates itself in no par- 

 ticular direction. The Tulip, Arum, 

 Gladiolus. &c., afford examples. 



(3.) The tuber is an irregular fleshy 

 body produced at the ends of the fibers 

 sent out from the root. They consist in 

 the Potato, which is the best example of 

 this variety, of buds imbedded in cellu- 

 lar substance, consisting principally of starch, which is to be- 

 come the food for the development of the buds. The buds are 

 what are commonly called the eyes of the potato, and they 

 form that part of it which is used by the farmer for propagating 

 this useful vegetable. 



(4.) The bulb is a leaf-bud inclosed in scales or concentric lay- 

 ers, and is found either at the base or summit 

 of the stem, or in the axils of the leaves; and 

 differs in no respect from the buds hereafter to 

 I..- described, but in separating itself from the 

 parent, and forming an independent individual. 



J'he Onion and Lily form examples of this va- 

 riety. Kg. 37 gives an illustration of the bulb. 

 The tree-onion, as it is called, bears bulbs on 



Cormus root. 



Fig. 87. 



W hut is a rhizoma ! The cormus ? The tuber ? Bulb ? 



