DISPERSAL OF SEEDS 



109 



Fleshy fruits, that is, such fruits as contain considerable water 

 when ripe, are eaten by animals and the seeds are passed off 

 undigested. Most wild fleshy fruits have small, hard, indigestible 

 seeds. Birds are responsible for scattering the seeds of many 

 berries and other small fruit. Bears and other berry-eating ani- 

 mals aid in this as well. Some seeds have especial adaptations 

 in the way of spines or projections. Insects use these projections 

 in order to carry them away. Ants plant seeds which they have 

 carried to their nests for food supply. Nuts are sometimes planted 

 by squirrels and blue jays. 



Hooks and spines. Some fruits which are dry and have a hard 

 external covering when ripe possess hooks or spines which enable 

 the whole fruit to catch in the coats of animals and are thus carried 

 away from the parent plant. Thus the whole fruit cluster may be 

 carried about and the seeds scattered. In many of the compos- 

 ites, as in the cockleburs and beggar-ticks, the fruits are provided 

 with strong curved projections which bear many smaller hooklike 

 barbs. 



Pappus. The dandelion is an example of a plant in which the 

 whole fruit is carried by the wind. The parachute, or pappus, is 

 an outgrowth of the ovary 



wall. Many other fruits, no- llfw^ I"** 



tably that of the Canadian 

 thistle, are provided with the 

 pappus as a means of getting 

 away from the parent plant. 

 In the milkweed the seeds 

 have developed a silky out- 

 growth which carries them long 

 distances from the parent plant. 



Dehiscent 1 fruits and how 

 they scatter seeds. One of the 

 many methods of scattering 

 seeds is seen in dry fruits. 

 These simply split to allow the escape of the seeds. Examples of 

 common fruits that split open, called dehiscent fruits, are seen in the 



1 ^Dehiscent (de-Ms'ent) : opening along a definite line to discharge contents. 



.centfaei* 



Jxxppurs- 



-ovctry 



oc single 

 /lower- 



How are the seeds of the Canadian thistle 

 scattered ? 



