30 THE PEANUT— THE UNPREDICTABLE LEGUME 



the initial growth between shoot and root. The root grows very rapidly, 

 reaching a mean length of 46 mm. in 4 days (Bouffil, 13) and 100 to 400 

 mm. in 4 to 5 days ( Yarbrough, 76) . During the first 2 days of this rapid 

 root growth no lateral roots develop (figure 2). But by the time the 



Figure 1. — Mature peanut seed. One cotyledon has been removed to show the 

 straight embryo with its well developed epicotyl and massive radicle. The papery 

 seed coat is visible around the edge of the cotyledon. 



seedling is 4 to 5 days old, 25 to 50 lateral roots have appeared (Yar- 

 brough, 77^. Figure 3 shows the hypocotyledonary axis grown to a 

 length of 164 mm. while the entire epicotyl has not exceeded the length of 

 the cotyledons, about 20 mm. ; in other words, an epicotyl-hypocotyl 

 ratio of J^. In 11^ days this root system reaches a length of 30 cm. and 

 produces 100 to 116 laterals (figure 10). Meanwhile the shoot expands 



