Gravatt: a Radish-Cabbage Hybrid 



271 



AN EXAMPLE OF HYBRID VIGOR 



Hybrid forms usually excel either of their parents in vigor, and agriculturists have long taken 

 advantage of this fact, in the production of both plants and animals. It is seldom, how- 

 ever, that so much extra energy is shown as by this cross between radish and cabbage, 

 neither of which ordinarily reaches great size. The cross continued growing for five 

 months after the above photograph was taken, and at the time it was killed by bacterial 

 rot, it had gone through the ventilator of the greenhouse and was traveling down the roof 

 on both sides. (Fig. 15.) 



The radish differs from the cabbage 

 in that it retains its open diffuse habit 

 of gro\\i:h. Instead of forming a soHd 

 head of leaves, it develops a tuberous 

 root and in this stores its surplus food. 

 Then when the radish reaches maturity, 

 a bloom stalk is sent up, being nourished 

 chiefly on stored food from the root. 



The hybrid has an open, diffuse gro^vth 

 habit. During the stage in which the 

 radish develops its root and the cabbage 



its head, the hybrid continues to develop 

 numerous large leaves. These leaves 

 are so thick that a large number of the 

 lower ones die and drop off, due to 

 lack of light. 



At first there is a single elongated 

 shoot, but sometime before blooming, 

 numerous side branches start out. In 

 figure 14, the side branches are just 

 starting. The main shoot develops into 

 a bloom stalk iust as in the case of the 



