PLANT ORGANS AND ORGANISMS 
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Differences Between Root and Stem 
The Root 
1. Descending axis of plant. 
2. Growing point sub-apical. 
3. Contains no chlorophyll. 
4. Branches arranged irregularly. 
5. Does not bear leaves or leaf rudi¬ 
ments. 
6. Structure comparatively simple. 
The Stem 
1. Ascending axis of plant. 
2. Growing point apical. 
3. Chlorophyll sometimes present. 
4. Branches with mathematical regu¬ 
larity. 
5. Bears leaves and modifications. 
6. Structure better defined. 
Classification of Roots as to Form.—1. 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. Examples: Taraxa¬ 
cum, Radish. 
2. Secondary roots are produced by the later growths of the stem, 
such as are covered with soil and supplied with moisture. Both 
primary and secondary roots may be either fibrous or fleshy. 
The grasses are good examples of plants haying 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 
abruptly 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. Examples: Roots developing on Bryophyllum and Begonia 
leaves when placed in moist sand. 
5. Epiphytic roots , the roots of epiphytes, common to tropical 
forests, for example, never reach the soil at all, but cling to the bark 
of trees and absorb nutriment from the air. Example: Roots of 
Vanilla. 
6. The roots of parasitic plants are known as Haustoria. These 
penetrate the bark of plants upon which they find lodgement, known 
