i84 THE STRUCTURE OF ECONOMIC PLANTS 



need several months to reach maturity and often attain a large size, 

 have a compact, firm flesh and can be successfully stored for some 

 time. 



The Root. — The root and hypocotyl constitute the succulent 

 portion of the plant which is generally eaten in the fresh state. 

 This fleshy axis is variable in size, shape, and color depending upon 

 the variety. The shape may be spherical, bluntly cylindrical, or 



Fig. 140. Radish plant in seed. (Courtesy Ferry-Morse Seed Co.) 



conical and much elongated; and the color ranges from cream- 

 white, pink, red, and variously mottled combinations to gray or 

 even black. 



Weaver and Bruner (lo) have pointed out that the development 

 of the root system is of an entirely different character in the round 

 or turnip-shaped varieties than in the half-long or long types. The 

 former are characterized by a rapidly growing tap root which may 

 penetrate the soil to a depth of x to 3 feet with a lateral spread of 

 IX to 16 inches. Most of the absorbing area lies in the upper 2. to 

 8 inches of surface soil; and, even in fully matured plants, only the 

 portion of the tap root occupying the first x to ix inches of surface 



