IOWA DEPARTMENT OF AGRICULTURE. 

 DESCRIPTION AND GENERAL CHARACTERISTICS. 



Alfalfa {Medicago sativa) is a number of the family botanically known as 

 the Leguminosse, to which also belong the clovers, peas, beans, vetches, 

 and other plants with pea-like blossoms and podded fruits. It is an up- 

 right, branching, smooth, perennial plant, growing from one to three feet 

 in height. Its stems are somewhat coarser in appearance than those of red 

 clover. The young plant sends up a single main stem. When this is cut 

 ofif and the plant grows older, more and more stems shoot up from near the 

 ground. In old plants that have been cut off many times the stems become 

 very numerous, sometimes as many as a hundred springing from a single 

 crown. The leaves are three parted, somewhat longer and much narrower 

 than those of red clover and somewhat toothed around the apex. 

 They are much more numerous than on red clover and are very nutritious. 

 The whole plant has a characteristic deep green color when in a healthy 

 condition, especially in a dry season. 



The small pea-like flowers are purplish to pinkish in color and are borne 

 in loose clusters or racemes along the smaller stems and branches. The 

 ripe seed-pods are spirally twisted, forming two or three complete curves, 

 and each pod contains several seeds. The seeds are kidney shaped, yellow- 

 ish brown in color, and about a half larger than red clover seeds. 



Like all members of the clover family, alfalfa has a strong tap root which 

 it sends deeply into the soil. These roots sometimes exceed an inch in 

 diameter, and in open soil often extends downwards to a depth of fifteen to 

 twenty feet, and much greater depths have been recorded. The great power 

 of alfalfa roots to penetrate hard soils is well illustrated on the experimental 

 farm here at LaFayette, where roots have been dug up which penetrated 

 through a foot and a half of hardpan, composed of fine silt and gravel, which 

 could hardly be broken up with a pick. As the root extends downwards, 

 numerous fine, lateral roots are produced, completely filling the soil and 

 extending the feeding area to immense proportions. This enormous de- 

 velopment of roots, and the great depth to which they penetrate, enables the 

 plant to gather food and moisture from depths not reached by ordinary plants. 

 Much mineral food is thus brought to the surface and the roots, when they 

 decay, leave the soil full of small, tube-like channels which faciliate drainage 

 and the aeration of the soil , a benefit which may be very considerable in close 

 textured soils. 



Alfalfa, like the clovers, has the power of assimilating the free nitrogen 

 of the atmosphere through the agency of bacteria which develop numerous 

 small nodules, or tubercles on its roots. These nodules contain millions of 

 bacteria which live on the juices of the root and in the process of their de- 

 velopment supply the plant with available forms of nitrogen which they have 

 the power to form from the practically unlimited supply in the air. This 

 gives the plant a very important additional value as a farm crop, since it 

 enriches the soil with large quantities of available nitrogen for the use of 

 succeeding crops. Thus where alfalfa is grown it will be necessary to supply 

 the soil with only mineral plant food; the alfalfa and its bacteria will look 

 after and increase the nitrogen supply. 



