SEED CHAEACTEES OF STJDAl!f GEASS AjSTD JOHNSON GEASS. 



What appear to be exceptions to the general rule of seed fail 

 occur in both kinds of seed, but the presence or absence of the 

 distinguishing suture is evident under a 

 good magnifier. I, 11 



DISTINGUISHING CHARACTERS OF THE 

 SEEDS OF SUDAN GRASS. 



Sudan grass seeds in the hull (fig. 3, ^) 

 vary from eighteen one-hundredths to 

 twenty-five one-hundredths of an inch in 

 length, exclusive of the short stem. Most 

 of the seeds bear at the base of each a 

 short stem (fig. 3, a), which is jaggedly 

 broken at its extremity. This stem repre- 

 sents the upper portion of a rachis segment 

 and is expanded at its articulation with 

 the spikelet, or seed. The articulation may 

 be marked by a slight constriction (fig. 3, 

 h), but it has no distinct suture. The ap- 

 pendages of the spikelet usually are jag- 

 gedly broken and not expanded at the 

 apex (fig. 3, c). The missing portion corre- 

 sponds to the short stem of the spikelet FiG.2.-Seed duster of Johnson grass, 

 , ., ^ enlarged: a, 0, Fertile spikelets; 6, 6, 



QeSCriDeCl. sterile spikelets; c, c, axis, or rachis. 



The seed hull is mainly straw colored of the duster; d,rf, pedicels of sterile 



. -._ . . flowers; «, f, sutures at the articula- 



or hght tawny. Many seeds are tmged tion of spikelets with the axis;/, 

 or spotted with brown. Some are tinged ^""^^^^ °f t^^ inflorescence bearing 



^ 1 • T 1 rrn 11 ^^^ ^^^^ cluster. 



or spotted with red. ihe darkest are 



blackish brown. In general, commercial seed has a smaller pro- 

 portion of reddish and blackish brown seeds than Johnson grass. 



The hulled grains 

 (fig, 3, S) vary from 

 thirteen one-hun- 

 dredths to eighteen one- 

 hundredths of an inch 

 in length and are light 

 reddish brown. They 

 are larger, more com- 

 monly elliptical in out- 

 line, and lighter colored 

 than in Johnson grass. 

 Even in the smaller 

 grains the embryo is r(ilativ(;ly larger than that found in Johnson 

 grass seeds. 



Flo . 3.— Sudan grass seeds, enlarged. Unhulled seeds , spikelets (1) ; 

 hulled grains (2;: a, a, Seed stem; 6, b, constriction at the junction 

 of seed and stem; c, e, appendages of the seed with broken apexes; 

 d, scar of the grain; c, embryo. 



