ROOT DEVELOPMENT OF CROP-PLANT ECADS. 



139 



and ran off horizontally or obliquely for 0.5 to 1.5 feet before turning down- 

 ward. These ultimately reached depths of 3 or 4 feet. Below the surface 

 1.5 feet lateral roots were more sparse. Near the rpot-tips, and especially 

 in the deeper soil, the branches were threadlike, and ran for several inches 

 without rebranching. A typical mature root system may be seen in figure 39. 



SUMMARY OF CROP PLANTS. 

 These data on root development in the two sites are summarized 

 in table 16: 



Table 16. — Development of crop plants. 



1 In order to secure greater accuracy in the ratios, these results were obtained directly from the 

 field notes where measurements were given in feet and inches. Table 16 gives the measurements 

 to the nearest tenth of a foot. In the ratios the root development in relation to height growth at 

 the lowland station is designated as unity. 



2 Cut July 8. 3 Uncut. * Average maximum height. 



CORRELATION OF CROP-ROOT DEVELOPMENT WITH THAT OF 

 NATURAL VEGETATION. 



An examination of table 16 shows that with all of the crop plants, 

 except three, the root penetration w T as as great or greater on the up- 

 land, while the root development in relation to the aerial part was con- 

 sistently greater than in the lowland. This relation, which agrees 

 with the root development of certain native species (p. 41), holds true 

 whether we determine the ratio from maximum root penetration or 

 from working depth. In seeking a cause for these differences, several 



