40 THE BOOK OF ALFALFA 



alfalfa. Both are of lower growth, as a rule, than alfalfa. 

 Both have wider leaflets, which, in Bur clover, are like 

 broad, inverted wedges. The flowers of these plants are 

 yellow, and are borne in scanty clusters. The pods are 

 wholly unlike those of alfalfa. While alfalfa has a spiral 

 pod of two or three turns, and containing often as many 

 as five or six seeds, Yellow trefoil has a straight pod, con- 

 taining but one seed. Bur clover has a coiled pod, but 

 covered with bristly projections that give the plant its 

 name. Where adulteration or substitution is practiced, 

 some of the pods of the substitutes are very apt to occur 

 in the bulk seed, and they can then easily be identified 

 and distinguished from those of alfalfa, 



^*Seed of Sweet clover seems to occur frequently in 

 western-grown alfalfa seed. The plant of Sweet clover 

 (illustrated) grows to a height frequently of from four 

 to six feet, bearing small, white flowers on slender spikes 

 three or four inches long. Unfortunately, and unlike 

 Yellow trefoil and Bur clover, Sweet clover is generally 

 rejected by stock. On this account, it is a plant of no 

 generally established value for hay or as pasture, 

 although, in some instances, it is successfully used. The 

 seeds of Sweet clover are of a golden yellow when ripe; 

 those of alfalfa, trefoil and Bur clover being greenish yel- 

 low. The seed coat of Sweet clover seed is covered with 

 minute elevations, while alfalfa seed is smooth. The 

 seeds of Sweet clover are rounder and plumper than those 

 of alfalfa, and have a very pronounced groove between 

 the main body of the seed and the ridge which marks the 

 location of the rootlet of the young plant within. It is 

 this ridge that in alfalfa seeds runs off, as a rule, in a 



