THE EVOLUTION OF PLANT REPRODUCTION 



11 



example clematis and dandelion — have feathery appendages 

 which sustain them in the air for great distances. Water-dis- 

 persed fruits are not common; the most typical case is that of the 

 coconut. This fruit develops an abundance of fibrous light mate- 

 rial which does not absorb water, and acts as a life-preserver for 

 the contained seed which is the coconut of commerce. 



Fig. 50. — Wind-dispersed fruits are generally small, light and dry; typical are 

 those of dandelion (A), maple (B), ash (C) and clematis (D). 



More ingenious is the production of fruits which involve an 

 explosive or propulsive mechanism for the ejection of the seeds 

 (fig. 51). In the touch-me-not, the fruit is an elongated capsule 

 whose wall separates at maturity into lengthwise sections while 

 remaining attached at the tip. When an object happens to touch 

 the tip of this capsule, it releases the segments, which uncurl 

 rapidly and act 2is sling-shots in throwing the seeds in all direc- 



