LEGUMINOSjE 443 



the variety. The average life is from five to seven years. 

 Fields 20 to 25 years old are found in the semi-arid sections. 

 At or near the ground level, is a short, compact stem (crown) 

 from which the numerous (20 to 50) branches arise (Fig. 186). 

 Blinn has shown that there is a well-defined relationship be- 

 tween the nature of the crown and hardiness. Non-hardy 

 types of alfalfa have an upright-growing crown with but few 

 buds and shoots developed below the soil surface. The crown 

 of hardy types is more spreading and the numerous buds and 

 shoots come from below the soil surface. Hence in the latter 

 case, the buds and young shoots are protected by the soil 

 from winter freezing. These hardy types are Grimm and 

 Baltic strains. The stems of alfalfa are rather slender and 

 freely branching. Common alfalfa has no rootstocks. 

 Some forms of Medicago falcata possess them, however, and 

 they also occasionally appear in some variegated tj^jes. 



"Cuttings" of Alfalfa.— The number of "cuttings" of 

 alfalfa depends upon the length of the growing season, and 

 the water supply. Three cuttings are usually made through- 

 out most of the alfalfa-growing regions of the United States. 

 In the Imperial Valley, CaUfornia, ordinary alfalfa has 

 yielded as many as nine cuttings in a year. This practice 

 indicates that alfalfa has the capacity of sending up numerous 

 shoots from the crown. The shoots of a second or third 

 crop begin to appear about the time the plant is coming into 

 bloom, and it is the usual practice to cut the crop at this 

 time, so that the food supply that would normally go into 

 developing fruit and seed, is diverted to the young growing 

 shoots of the succeeding crop. Furthermore, the leaves are 

 richest in nutritive substances when the plant is in bloom. 

 The leaves contain about 80 per cent, of the protein in the 

 plant, hence methods of harvesting should look toward the 

 prevention of their loss. The different cuttings of alfalfa 



