14 GRASSES OF IOWA. 



the corn seems to be a shallow-rooted plant, as much by 

 reason of the obstacles which the roots encountered in grow- 

 ing downward, as by any habic characteristic of the plant. 

 Other observations, to wh'ch attention will be called later, 

 indicate that in looser soils corn roots grow to a much greater 

 depth than was observed in this locality." 



Since this above was written, King* has made a careful 

 study of the root development of corn, from which it appears 

 that forty-two days after planting the roots had penetrated a 

 depth of eighteen inches. The surface roots sloped gently 

 downward toward the center of the row, where those nearest 

 the surface were some inches deep When corn was three 

 feet high the roots occupied the entire soil down to a depth of 

 two feet. 



' ' Here the roots are seen to occupy the entire soil down lo a 

 depth of two feet, which is the height of the cage. At this 

 stage the surface leaders descend in a gentle curve toward the 

 center of the row where they pass each other and lie only six 

 inches deep. 



"Just as the corn is coming into full tassel a third sample 

 was taken which is represented in figure 10, and here it will 

 be seen the roots have fully occupied the upper three feet of 

 soil in the entire field. In the center of the row, too, the sur- 

 face leaders have risen still higher, and a few of them are now 

 scarcely five inches deep, though the great bulk of them are 

 still six inches or more below the surface at the center." 



Concerning the distribution of th^ roots of our forage 

 grasses very little definite is known, since few experiments 

 have been made. The roots of blue grass during the spring 

 and early summer are more or less horizontal and these 

 spread obliquely downward in the soil. The grass makes 

 little growth during dry weather for the reason that the 

 majority of the roots occur in the surface soil. The well 

 developed rhizomes maintain its vitality. The roots of annual 

 grasses like Setaria, Panicnm cajnllare, and P. sanguinale are 

 developed in a manner similar to corn. 



The Stem. 



Gross character. — Grass stems are always branched at the 

 base, and occasionally in their upper portions. If the branches 

 are all apparently at the root, the culms are said to be simple, 



Annual Rep. Wis. Agrl. Exp. Sta. 9; 113. 



