1 6 PHARMACEUTICAL BOTANY 



DIFFERENCES BETWEEN ROOT AND STEM 



The Root The Stem 



L. Descending axis of plant. i. Ascending axis of plant. 



2. Growing point sub-apical. a. Growing px)int apical. 



3. Contains no chlorophyll. 3. Chlorophyll sometimes present. 



4. Branches arranged irregularly. 4. Branches with mathematical regularity. 



5. Does not bear leaves or leaf rudi- 5. Bears leaves and modifications. 



ments. 



6. Structure comparatively simple. 6. Structure better defined. 



Classification of Roots as to Form.— ^i . Primary or first root, a 

 direct downward growth from the seed, which, if greatly in excess of the 

 lateral roots, is called the main or tap root. Ex. : Taraxacum, Radish. 



2. Secondary roots are produced by the later growths of the stem, 

 such as are covered with soil and supplied with moisture. Both pri- 

 mary and secondary roots may be either fibrous or fleshy. 



The grasses are good examples of plants having fibrous roots. 

 Fleshy roots may be multiple, as those of the Dahlia, or may assume 

 simple forms, as follows: 



Fusiform, or spindle-shaped, like that of the radish or parsnip. 



Napiform or turnip-shaped, somewhat globular and becoming ab- 

 ruptly slender then terminating in a conical tap root, as the roots of 

 the turnip. 



Conical, having the largest diameter at the base then tapering, as 

 in the Maple. 



3. Anomalous roots are of irregular or unusual habits, subserving 

 other purposes than the normal. 



4. Adventitious roots are such as occur in abnormal places on 

 the plant. Ex. : Roots developing on Bryophyllum leaves. 



5. Epiphytic roots, the roots of epiphytes, common to tropica] 

 forests, for example, never reach the soil at all, but cling to the bark 

 of trees and absorb nutriment from the air. Ex. : Roots of Vanilla. 



6. The roots of parasitic plants are known as haustoria. These 

 penetrate the bark of plants upon which they find lodgment, known 

 as hosts, and absorb nutritious juices from them. The Mistletoe, 

 Dodder and Geradia are typical parasites. 



Duration of Root. — 'Plants are classified according to the duration 

 of the root, as follows: 



I . Annual plants are herbs with roots containing no nourishment 

 for future use. They complete their growth, producing flower, fruit and 

 seed in a single season, then die. 



