Testing Farm Seeds. 353 



Weed seeds occurring in farm seed are of interest to the buyer of 

 seed (1) in respect to their total quantity and (2) in respect to their 

 kinds. In many instances low-grade seed contains so much weed seed 

 that the quantity of the crop seed is thereby greatly reduced in a given 

 weight of seed. Of the kinds of weed seeds 300 to 400 are known to occur 

 in the various kinds of the common crop seeds. Occasionally from 75 to 

 100 kinds of weed seeds are to be found in a single sample of red clover 

 or alfalfa seed not exceeding a few ounces in weight. In some instances 

 one or more kinds of weed seed are very abundant in the sample. As a 

 rule, however, most of the kinds are represented by only a few seeds. 



The important question in regard to the kinds of weed seeds found 

 in crop seed is whether the plants they produce are injurious or relatively 

 unimportant. Some of the weed seeds commonly found in seed produce 

 plants which are very detrimental to the crop or to the land. Everyone 

 making tests of seed should become familiar with the seeds of injurious 

 weeds. Most of the weed seeds found in making tests are seeds of com- 

 paratively harmless plants, and their recognition as to kind becomes more 

 a matter of interest than one of practical importance. ' 



Certain kinds of crop seeds, as clover, alfalfa, awnless brome-grass, 

 etc., are supplied to the American market from both foreign and domes- 

 tic sources. Since domestic seed is generally preferable to that which is 

 imported, the source of the seed, as indicated by the weed seeds it con- 

 tains, gives an added interest to some kinds of weed seeds. Thus the 

 presence of seeds of perhaps several kinds of native weeds in a sample of 

 clover seed or of alfalfa seed, together Avith the absence of seeds common- 

 ly found in imported seed, practically amounts to proof of its domestic 

 production. Foreign production is strongly suggested by reverse condi- 

 tions. Many kinds of weed seeds found in imported seed grow and pro- 

 duce plants in this country, it is true, but the growth or seed production 

 of the plants is so meager or is so restricted to certain localities that their 

 seeds rarely or never appear in the American-grown seed crop. When 

 such seeds appear as several kinds together, or in abundance, they practi- 

 cally prove the foreign origin of the seed containing them. 



The illustrations of weed seeds presented here show the seeds classi- 

 fied (1) as noxious weed seeds found in farm seed (figs. 17 and 18) and 

 (2) as other weed seeds commonly found in farm seeds (figs. 19, 20 and 

 21). The figures, together with the brief descriptions of distinguishing 

 characters, should enable one readily to recognize these seeds when ex- 

 amined with a magnifier. Weed seeds that are found with the several 

 kinds of clover, grass and cereal seeds are mentioned under the subse- 

 quent discussion of the testing of these crop seeds. 



A — 23 



