SUDAN" GRASS AND RELATED PLANTS. 



57 



Fig. 24.— Sudan grass seeds, enlarged. Unhulled seeds, spikelets (1); 

 hulled grains (2): a, a, Seed stem; 6, 6, construction at the junction 

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

 d, scar of the grain; e, embryo. 



The contrasting characters of the two seeds, as described by Hill- 

 man, are set forth in Table XIX. 



It will be noticed that there is an overlapping in several of these 

 characters, particularly in the size and color of the unhulled seeds; 

 also that a small percentage of Sudan grass seeds has no portion. of 

 the rachis adhering and 

 an equally small per- 

 centage of Johnson grass 

 seeds is found in which 

 a portion of the rachis 

 adheres. In all such 

 cases, however, Hill- 

 man declares that an 

 examination of the seed 

 surface at the point of 

 attachment, the size of 

 the seed, together with 

 the size, form, and color 

 of the grain, should suffice to distinguish the seed of one grass from 

 that of the other. Most States now have seed laboratories in connec- 

 tion with their agricultural experiment stations. By referring sam- 

 ples of all Sudan grass seed importations to the analysts in these 

 laboratories the seed dealer may ascertain whether these samples 

 are free from Johnson grass seed. 



CULTURAL METHODS FOR SEED PRODUCTION. 



Most Sudan grass seed is produced in cultivated rows, because this 

 method of planting with its accompanying cultivation more nearly 



assures a crop, especially 

 in regions subject to 

 drought. Table XX 

 shows the yields obtained 

 in both wide and narrow 

 rows, as compared with 

 broadcast or close drills. 

 Table XX shows that 

 cultivated rows give bet- 

 ter yields of seed in the 

 humid regions and also in 

 the semiarid regions if the 

 crop is not irrigated. Un- 

 der irrigation the results are reversed, the broadcasted or close-drilled 

 seedings being markedly superior. Narrow rows, 18 to 24 inches apart, 

 give larger yields than the wide rows, 36 to 44 inches apart, but it is 

 hardly advisable for a farmer to plant in narrow rows unless he has on 

 hand machinery adapted for their cultivation. Wide rows can be 



Fig. 25. — Johnson grass seeds, enlarged. Unhulled seeds, spikelets 

 (1); hulled grains (2): a, a, Scar of the hull; b, b, appendages of 

 the seed with expanded, cup-shaped apexes; c, scar of the grain; 

 d, embryo. 





