78 



Principles of Plant Culture. 



the surface, and in a tall-growing southern corn, roots 

 of considerable size started at a depth of only half an 

 inch. The main root of a Hubbard squash vine was 

 traced a distance of ten feet, in which its depth varied 

 from two to five inches. In tobacco fields, the rootlets 

 sometimes literally protrude from the surface of the soil 

 in warm, wet weather (231). 



no. The Rate of Root Growth in rapidly develop- 

 ing plants is often extremely fast. President Clark, 

 formerly of the Massachusetts Agricultural College, 

 concluded from very careful examinations and measure- 

 ments of the roots of a 

 squash vine grown un- 

 der glass, that rootlets 

 must have been pro- 

 duced at the rate of at 

 least one thousand feet 

 per day during the lat- 

 ter part of the growth 

 period. \. 



in. Relation of 

 Roots to Food Supply. 

 In the extent of ground 

 occupied, root growth is 

 relatively less in moist 

 and fertile soils than in 

 poorer and drier ones, 



FIG. 33. Young clover plant show- but the roots are pro- 



na s ture u r c ;From p or t i on a t e 1 y more 



branched. In wet seasons, a given plant has less ex- 

 tensive root development than in drier seasons, because 



