OP AGRICULTURE. 19 



peculiar secretions of the plant. The germs, oil, etc., 

 are secreted by glands. 



ROOTS. 



The roots serve the double purpose of sustaining the 

 plant in its proper position and of absorbing from the 

 soil its appropriate food. Their office being some- 

 what similar to that of the mouths of animals, they 

 take in both food and water. 



Eoots have a great variety of form : first, the ramose, 

 or branching, as those of trees or shrubs ; second, the 

 spindle, as the radish or parsnip ; third, tuberous, closely 

 resembling the potato, formerly regarded a tuberous 

 root; but the proper tuberous root has no eyes or 

 buds, while the potato has, and. therefore, is properly 

 classed with the underground stems ; fourth, fibrous. 

 Wheat, corn, and most of the grasses have fibrous 

 roots; Indian corn has, in addition,, a still different 

 kind of root, called brace roots. They serve to sup- 

 port the plant, and at the same time collect nourish- 

 ment from the soil. 



Parts of the Hoot. Tap root is the main body of 

 the root, generally descending vertically into the soil. 

 The fibrils are branches off from the tap root, often 

 passing into many subdivisions. The soft, spongy, 

 pulpy points of the branch roots are the mouths, 

 through which the plant absorbs its food from the 

 soil. 



THE S T E M . 



* The ascending of the stem, and the descending of 

 the tap root, seem to be owing chiefly to the mys- 

 terious influence of light. This can be shown by cxperi- 



