38 



THE ROOT. 



Rhizoma root. 



Fig. 36. 



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

 tal direction, emitting roots 

 from its under side, increas- 

 ing by one extremity only, 

 at which it puts forth leaves 

 and flower-stems, and gradu- 

 ally dying at the other. Its 

 surface is generally marked 

 b} irregular ridges formed by 

 th.3 bases of decayed leaves. 

 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 

 be described, but in separating itself from the 

 parent, and forming an independent individual. 

 The Onion and Lily form examples of this va- 

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

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



Cormus root. 



What is a rhizoma ! The cormus ? The tuber ? Bulb ? 



