6 THE BOOK OF ALFALFA 



ITS WONBEBFUL BOOT SYSTEM. 



In Its root growth it is probably the greatest wonder 

 among plants. While it usually grows no higher than 

 four or five feet (although it has been known to reach 

 more than ten feet ; an unirrigated stalk is on exhibition 

 at the office of the Kansas Board of Agriculture, measur- 

 ing nearly seven feet) and its normal height is about 

 three feet, its roots go down ten, twenty, or more feet, 

 and one case in Nevada is reported by Charles W. Irish, 

 chief of Irrigation Inquiry United States Department of 

 Agriculture, where the roots were found penetrating 

 through crevices in the roof of a tunnel one hundred 

 and twenty-nine feet below the surface of an alfalfa field. 

 Prof. W. P. Headden of Colorado found roots nine feet 

 long from alfalfa only nine months old, and another 

 reports roots seventeen inches long of but four weeks' 

 growth, the plants being but six inches high. It usually 

 has a slender taproot, with many branches tending 

 downward, yet with considerable lateral growth. As the 

 taproot is piercing the earth it is also sending out new 

 fibrous roots, while the upper ones, decaying, are leav- 

 ing humus and providing innumerable openings for air, 

 the rains, and fertilizing elements from the surface soil. 

 The mechanical effect of this root-growth and decay in 

 the soil constitutes one of the greatest virtues of the 

 plant, and by its roots alfalfa becomes, self-acting, by far 

 the most efficient, deep reaching subsoiler and renovator 

 known to agriculture. 



VABIETIES AND PEOUIilARITIES. 



There are several other varieties of alfalfa besides 

 Medicago sativa, the most common being the Interme- 



