72 FORAGE PLANTS AND THEIR CULTURE 



obsolete. At one time in Europe particles of quartz 

 were prepared and colored especially to adulterate 

 clover seed. In England there was a regular business in 

 the collecting and killing of weed seeds to be used as 

 adulterants. 



Among the seeds that are still often adulterated are red 

 clover, alfalfa, alsike, Kentucky blue-grass, orchard-grass, 

 redtop, meadow fescue and brome-grass. 



64. Color and plumpness of seeds. Depending on 

 the conditions under which it was grown, there is much 

 difference in seeds as to brightness of color and degree of 

 plumpness. 



Shriveled seeds make weak seedlings, but no field experi- 

 ments where shriveled were compared with plump seeds 

 seem to be recorded. 



Discolored seed is evidence that the seed is old, or has 

 been badly stored, or more usually that it was harvested 

 under unfavorable conditions. 



65. Age of seed. Seeds vary greatly in the length 

 of time they will retain their germinating power. In gen- 

 eral, the seeds of legumes are much longer lived than those 

 of grasses. Old seeds make weaker seedlings than fresh 

 seeds, and this probably has its effect on the resultant yield. 



In red clover and other legumes the germination of 

 fresh seeds is usually less than that of seeds one year old, 

 owing to the presence of " hard " seeds. ( 71.) 



Cowpea seeds, at least some varieties, also refuse to 

 germinate when fresh unless the testa is broken or scratched 

 with sand. Apparently there is a waterproof coating 

 that for a time prevents the absorption of water. 



The results obtained during many years at the Zurich, 

 Switzerland, Sqed Control Station, show that few forage 

 seeds are worth planting when three years old. 



