238 HOW CROPS GEOW. 



upper portion of the tap-root of the beet, turnip, carrot, 

 and radish, expands under cultivation, and becomes a 

 fleshy, nutritive mass, in which lies the value of these 

 plants for agriculture. The lateral roots of other plants, 

 as of the dahlia and sweet potato, swell out at their ex- 

 tremities to tubers. 



Crown Roots I — MonocotyUdonous plants, or Endogens, 

 i. e., plants whose seeds do not split with ease into two 

 nearly equal parts, and whose stems increase by inside 

 growth, such as the cereals, grasses, lilies, palms, etc., 

 have no single tap-root, but produce crown roots, i. e., 

 a number of roots issue at once in quick succession from 

 the base of the stem. This is strikingly seen in the onion 

 and hyacinth, as well as in maize, 



RootletSi — This term we apply to the slender roots, 

 usually not larger than a knitting needle, and but a few 

 inches long, which are formed last in the order of growth, 

 and correspond to the larger roots as twigs correspond to 

 the branches of the stem. 



The Offices of the Root are threefold : 



1. To fix the plant in the earth and maintain it, in most 

 cases, in an upright position. 



2. To absorb nutriment, from the soil for the growth of 

 the entire plant, and, 



3. In case of many plants, especially of those whose 

 terms of life extend through several or many years, to 

 serve as a store-house for the future use of the plant. 



1, The Firmness with which a Plant is fixed in the 

 Ground depends upon the nature of its roots. It is easy 

 to lift an onion from the soil, a carrot requires much more 

 force, while a dock may resist the full strength of a pow- 

 erful man. A small beech or seedling apple tree, which 

 has a tap-root, withstands the force of a wind that would 

 prostrate a maize-plant or a poplar,which has only side roots. 

 In the nursery it is the custom to cut off the tap-root of 



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