284 



FREAKS OF PLANT LIFE. 



many instances by the hygroscopism of some of the 

 parts. Although this usually takes place in dead 

 tissues, some of the instances are of interest in this 

 connection. One of the best known is the fruit of the 

 sand box-tree (Hum crepitans). The capsule is about 

 the size of an orange, and consists of a number of 

 carpels, packed together side by side. When dry 



the carpels separate, 

 and fly apart with a 

 loud report. When 

 once separated they 

 cannot be com- 

 pressed again into 

 their original form. 

 These capsules were 

 formerly used as 

 " sand - boxes," be- 

 fore the invention of 

 blotting paper, but 

 had to be bound to- 

 gether in order to pre- 

 vent their sudden de- 

 hiscence. It was not 

 unusual for them to fly in pieces after many years. 



The pods of some plants of the pea and bean 

 family (Leguminosce) have a tendency to separate at 

 the valves, and become twisted or curl backwards 

 with considerable force. The large pods of an 



Fig. 52.— Sand-box {Hum crepitans). 



