78 



PLANTS AND MAN 



tions. Among members of the pea and bean family, the drying of 

 the pod often results in a twisting and breaking of the fruit so that 

 the seeds (the peas or beans) are forcibly ejected. Few of the wind- 



A B 



Fig. 51. — Some fruits involve explosive or propulsive mechanisms for seed 

 dispersal, as in touch-me-not (B) and wild geranium (A). 



dispersed, water-dispersed or mechanically-operated fruits have 

 become of economic importance as foods for man, since in most 

 cases the fruit is dry, small, and possesses little if any stored food. 

 The exception is found among the cereals, but in reality the food 



Fig. 52. — Many animal-dispersed fruits have hooks or barbs for attachment to 

 animals; examples include beggar ticks (A), tick trefoil (B), burrs (C). 



value in this case depends upon the seed rather than the fruit 



which is thin-walled, dry and an insignificant part of the grain. 



Animal dispersed fruits have succeeded in a variety of ways in 



using animals for seed distribution. In some cases these fruits are 



