Dec. 15, 1914 



Seeds of Agropyron 



277 



pronounced when Agropyron seeds become so mutilated that portions 

 of the glumes are destroyed, as is frequently the case in commercial 

 seed mixtures. In some cases the glumes are entirely gone, leaving 

 only the grain, and determinations according to characters described 

 below then become impossible. No satisfactory method of real prac- 

 tical value has yet been worked out whereby the seeds without the 

 glumes may be accurately determined, and it seems probable that in 

 such cases one may be compelled to resort to microscopic sections. 

 One characteristic difference may be noted, however — namely, that 

 the color of the matured grain of .4 . tenerum is somewhat lighter than 

 that of either A . repens or A . smiihii. The two latter approximate each 

 other closely in color. 



SOURCE OF SEEDS 



Materials for this work were secured from as many sources as possible, 

 as given in Table I. Only those samples have been considered which 

 were obtained from and determined by a competent botanist, who was 

 sure of the origin of the seed. 



Table I. — Sources of seeds of Agropyron s/^p. used in investigation 



Source of seed. 



A. repens. 



A. smithii. 



A. tcnemin. 



Canada (Manitoba;. . 

 Illinois (Chicago) ^. . 



Iowa 



Michigan 



Minnesota 



New York (Geneva). 



North Dakota 



North Dakota b 



Russia * 



Washington (State). . 



Wisconsin 6 



Wisconsin 



Wyoming 





(a 



n 



(a) 



(a) 



8 



■(°y 



(a) 



" Sample received. 



^ From Seed Laboratory of United States Department of Agriculture, Washington. D. C. 



LABORATORY METHODS OF IDENTIFICATION 



It is obviously necessary that all methods of identification, especially 

 for use by farmers or seedsmen and even for seed laboratories, be as 

 simple as possible and that they do not require elaborate or expensive 

 apparatus. If, however, the distinguishing characters are not visible 

 to the naked eye or with the aid of an ordinary magnifying glass, then it 

 becomes absolutely necessary to use a higher power of magnification. 



In the identification of seeds of Agropyron spp. it is advisable to use a 

 magnification of about 32 diameters for the best results. The Greenough 

 binocular giving the stereoscopic view has proved very satisfactory. 

 It is absolutely necessary when examining seeds under the lens to place 

 them so that the base of the seed is toward the light, in which position 

 the light will be properly reflected from the hairs, making them appear 

 clear and well defined. 



