64 FARM AND SCHOOL PROBLEMS. 



the second year in producing a crop of seed. The second year 

 the root is dry and tasteless. 



It is the new and delicate parts of roots that perform the 

 office of absorption; hence we should take great care in preserv- 

 ing the fine roots or fibrils of plants that are to be transplanted. 

 (Let the pupils examine carefully the root-hairs of a young radish 

 plant, or of a young corn plant.) 



But roots are not always necessary to start plants. House 

 plants, alfalfa, clover and other plants can be grown from cut- 

 tings. Currants, grapes, cottonwoods, and willows are often prop- 

 agated by cuttings, and even leaves of certain plants will form 

 roots and grow new plants. 



Old roots do not perform much of the work of absorption; 

 their chief purpose is to carry food absorbed by the young roots 

 and to hold the stem in a fixed location and position. The sap in 

 the cells of young roots secretes an acid that passes from the 

 root to the soil and aids in the preparation of food. This acid 

 dissolves certain constituents of the soil, such as carbonate and 

 phosphate of lime which are then absorbed by osmosis. 



In leguminous plants we find roots performing still another 

 function. The roots become the media through which bacteria 

 perform an important service for the agriculturist, in preparing 

 food for plants. Bacteria form the nodules on the roots of beans, 

 cowpeas, clover, alfalfa, and vetches. When soil is without avail- 

 able nitrogen, these minute organisms take the nitrogen of the 

 air in the soil and prepare a nitrogen compound that can be 

 used by the plant. Thus leguminous plants and bacteria supply 

 the soil with the nitrogen necessary for the growth of other plants. 



The chief function of the root is to bring food from the 

 soil to the plant in the soluble form. Hence plants require a 

 prodigious amount of water. 90 per cent of the green plant 

 is water. It is necessary to understand by what means this 

 water is conducted from the soil to the body of the plant. 



An examination of a transverse section of a root, reveals 

 the facts pertaining to the functions of roots. At the extremity 

 of the root is the root-cap made up of old cells that are rubbed 

 off as the root forces its way through the soil. Roots prepare 



