GRASSES OP IOWA. 13 



result of some work carried on with Gilbert that only one one- 

 thousandth of the roots of corn enter the subsoil. Armsby 

 also observes that in a stiff clay soil few of the roots of corn 

 enter the subsoil. Thiel also observes that in our cultivated 

 plants most of the fine roots which supply the plant with min- 

 eral matter occur in the upper strata. Hunt,* in commenting 

 on some experiments made in Illinois, says: 'Two-thirds of 

 the roots would have been broken by root pruning four inches 

 deep; more than two-fifths would have been broken at three 

 inches deep; and one-seventh at two inches deep.' Newmanf 

 observes that most of the roots are within four inches of the 

 surface; these roots severed from the plant will deprive it of 

 three-fourths of its nourishment. " 



Hayst says: "Returning to the direction or spread of the 

 roots in the soil, those of the first whorls, say the five lower 

 ones, start out nearly horizontally. This is in accordance with 

 certain facts, viz: at this season of the year surface soil is 

 warm, while the subsoil is yet cold; the upper soil is also 

 richer in plant food and usually contains at this season an 

 abundance of moisture. "We ses at 1, 2 and 3, plate I, that all 

 the roots go nearly horizontally, and a cultivator running four 

 to six inches deep, and the same distance from the hill, would 

 sever most of these roots. After about the fourth week we 

 find these primary roots changing their course, however, for 

 having heretofore pushed outward they now grow downward, 

 soon taking a nearly vertical direction. Not alone the roots 

 which first grew outward, but all those now starting from the 

 nodes above as well, take this downward course from the very 

 beginning. ' ' 



Armsby§ states as the result of some work carried on under 

 his direction by Hickman: " Concerning the direction of the 

 growth, a few words may be written, although the plan of the 

 experiment did not include accurate observations and meas- 

 urements upon this point. It was observed that the nodal 

 roots, and especially those later formed, branched out hori- 

 zontally from the stem for a considerable distance, and then 

 turned downward quite rapidly. In the stiff soil in which the 

 plants were grown, few of the roots appeared to enter far into 

 the subsoil, which is a very stiff clay, so that in this situation 



♦Bull. University of 111. Agrl. Exp. Station. 13: 427, 1891. 

 +Bull. Alabama A(?rl. Exp. Station. 4: 1887. 

 JPrairie Farmer 1887: 373. 631; Bull. Minn. Agrl. Exp. Sta., 5: 

 SAnn. Rep. Penn. State Coll. 1886:97. 



