ROOT DEVELOPMENT OF CROP-PLANT ECADS. 



137 



Red clover (Trifolium pratense). — The 



first examination of the roots of red clover 

 was made on July 10, at a time when the 

 plants in the lower and upper plats were 

 1 and 0.8 foot in height respectively, and 

 in full bloom. As usual, numerous plants 

 were examined on each site. In the low- 

 land soil some tap-roots with a diameter 

 of 5 mm. were traced to a depth of 3.6 feet. 

 The strong tap-roots penetrated almost 

 vertically downward, but tapered so 

 rapidly that at a depth of 6 to 8 inches 

 they were seldom more than a millimeter 

 thick. Beginning 3 to 4 inches below the 

 soil surface and to a depth of 1.5 feet, 

 numerous branches were given off. Some 

 of these extended laterally for distances 

 of 8 to 12 inches before turning downward. 



Fig. 38. — Root system of Trifolium pratense about 

 2.5 months old. 



Fig. 39. — Mature root system of 

 Trifolium pratense. 



