Dispersion of Fruits and Seeds. 



211 



The behavior of the seed pods of the wild and cultivated 

 touch-me-nots is familiar to every one. Here the valves 

 of the pods suddenly coil elastically when touched, and 

 scatter the seeds. 



In many plants the carpels break apart in such a way as 

 to allow the seeds to lie loosely in them, so that when the 

 plant is violently shaken by 

 the wind, or when it sud- 

 denly rebounds after being 

 bent down by passing ani- 

 mals, the seeds are thrown 

 from their position. In 

 many composite plants the 

 dry fruits which he loosely 

 on the receptacle are scat- 

 tered in this way, the stems 

 having become dry and 

 elastic by the time the 

 fruits have ripened. 



A very curious case where 

 the elasticity of succulent 

 tissues is employed is found 

 in the squirting cucumber 



(Fig. 126). When the fruit ripens, a portion of it in the 

 form of a plug continues with the stalk, becomes sepa- 

 rated from the surrounding tissues while still remaining 

 attached to the stalk, and is drawn out like a stopper 

 when the fruit drops off. Then the swollen mucilaginous 

 contents which had kept the walls of the fruit in a state of 

 tension are forcibly ejected, together with the seeds, by 

 the sudden contraction of the walls. 



146. Dispersion by Winds. — A common device designed 

 to employ the wind as an agent of dispersion is found in 



Fig. 126. 



A branch of squirting Cucumber, showing 

 a fruit falling off and ejecting the seeds. 

 After Kerner. 



