1 86 Fruits and Seeds. 



common Broom, throw their seeds, owing to the 

 elasticity of the pods, which, when ripe, open sud- 

 denly with a jerk. Each valve of the pod contains 

 a layer of woody cells, which, however, do not pass 

 straight up the pod, but are more or less inclined 

 to its axis (fig. 72). Consequently, when the pod 



Fig. 72. Pod of the BUSH VETCH. 

 The line a b shows the direction of the woody fibres. 



bursts it does not, as in the case of the Bittercress, 

 roll up like a watch-spring, but twists itself more 

 or less like a corkscrew. 



5. I have mentioned these species because they are 

 some of our commonest wild flowers, so that during 

 the summer and autumn we may, in almost any 

 walk, observe for ourselves this innocent artillery. 



