56 



BULLETIN 981, TL S. DEPARTMENT OF AGRICULTURE. 



it was impossible to ascertain by seed inspection whether it was 

 adulterated with Johnson grass seed. F. H. Hillman, after a critical 

 study of the seeds of the two grasses, published (11) complete instruc- 

 tions for their identification. The method is based chiefly on the 

 character mentioned by Oakley, that of the attachment of the seed to 

 the rachis branch, but this was amplified and explained by drawings 

 in a way which now makes it possible, at least for a trained seed 

 analyst, to identify the two seeds with reasonable certainty. (Figs. 

 24 and 25.) 





Fig. 23.— Seeds of Johnson grass (1) and Sudan grass (2). Hulled grains appear at theleft of each group. 

 (Natural size, from a photograph.) 



Table XIX. — Distinguishing characters of the seeds of Sudan grass and Johnson grass. 



Kind of seeds. 



Length of seeds. 



Prevailing color. 



Unhulled. 



Hulled. 



Hulls. 



Hulled seeds. 





Inches. 

 0. 18 to 0. 25 



0. 15 to 0. 22 



Inches. 

 0. 13 to 0. 18 



0. 08 to 0. 12 



Straw or light tawny, 

 some reddish and 

 some blackish 

 brown. 



Blackish brown, some 

 reddish and some 

 straw color. 



Light reddish brown. 









Kind of seeds. 



Character of the — 



Apex of the seed 

 appendages. 



Shape of the hulled 



Attachment of 

 seeds. 



Embryo. 



seed. 



Sudan grass 



No distinct suture 

 or scar tissue; 

 portion of rachis 

 segment usually 

 adhering. 



Distinct suture or 

 scar; usually no 

 rachis segment 

 adhering. 



Relatively large. 



Smaller and nar- 

 rower than that 

 of Sudan grass. 



Jaggedly broken, 

 not expanded. 



Smooth, expand- 

 ed, cup shaped. 



Elliptical in out- 

 line. 







oval-'elhptical. 



