40 THE BOOK OF ALFALFA 



seeds measure 0.0604 inch by o. 1188 inch, as compared 

 with an average for alfalfa of only 0.0582 inch by 0.0944 

 inch. 



"So far as the plants of Yellow trefoil and Bur clover 

 are concerned, they are easily distinguishable from 

 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. Alfalfa has a spiral pod 

 of two or three turns (p. 32), containing as many as 

 five or six seeds. Yellow trefoil has a straight pod (p. 

 32), containing but one seed. Bur clover has a coiled pod 

 (p. 33), but covered with bristly projections that give the 

 plant its name. Where adulteration or substitution is 

 practiced, some of the pods are very apt to occur in the 

 bulk seed, and they can then easily be identified and dis- 

 tinguished from those of alfalfa. 



"Seed of Sweet clover seems to occur frequently in 

 western-grown alfalfa seed (p. 26). Sweet clover (il- 

 lustrated in this book) 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 



