8 ALFALFA 



year. The diameter of the top was eighteen inches, 

 and the number of stems 360. The pidlure shows 

 how these crowns gather soil around them, for the 

 length of the undergrouiid stem is seen to be several 

 inches, and this represents the accumulation of nearly 

 this much material about the plant. This is one of 

 the largest plants yet found. The specimen as photo- 

 graphed was probably six years old. The root system 

 at first consists of a simple tap-root with numerous 

 small lateral branches. The main root often divides 

 a few inches or a greater distance below the crown, 

 and such divisions occur several times as the root 

 extends downward (Fig. 3), but the main parts of 

 the root grow dpwnwafd rather than laterally, as seen 

 in Fig. 4. 



As the crown becomes broader from the extension 

 of the lateral branches, new roots are sent down from 

 these stems, until after several years as many roots 

 may be found descending from what was originally a 

 single stalk. These lateral branches often become 

 mutilated, accidentally by the trampling of animals or 

 intentionally by use of the disk-harrow, and a portion 

 of a stem is made entirely dependent upon the root 

 descending from it, and becomes an apparently inde- 

 pendent plant. This fadl makes the disk-cutter an 

 important means of greatly increasing the number of 

 plants in a field. When the stems which grow above 

 ground are cut or grazed off closely they die down to 

 the underground stem, or crown, and new branches 

 are produced from new buds. This method of growth 

 explains why alfalfa is so often injured by continuous 

 close grazing. The stems of most other foliage plants, 

 when cut or grazed ofi^, branch out from lateral buds 



