ELEVENTH ANNUAL YEAR BOOK— PART XI 727 



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 in- 

 stances 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 relativelj 

 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 injur- 

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

 of comparatively 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 domestic 

 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 with the absence of seeds com- 

 monly found in imported seed, practically amounts to proof of its domes- 

 tic production. Foreign production is strongly suggested by reverse con- 

 ditions. 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 

 practically 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 seeds (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. 



NOXIOUS WEED SEEDS FOUND IX FARM: SEEDS. 



The following brief descriptions point out the most conspicuous dis- 

 tinctions between the seeds of various noxious weeds. They only supple- 

 ment the illustrations to which they refer and which show the general 

 form and structure and the natural size of the seeds. The serial order is 



