288 



STUDIES IN SEEDS AND FRUITS 



Method of 

 determining 

 the stage at 

 which dehis- 

 cence of 

 legumes 

 occurs, such 

 as those of 

 Vicia, Ulex, 

 and Cassal- 

 pinia. 



As illustrating the dehiscence of typical legumes, I will take 

 the behaviour of the pods of Vicia sativa, Ulex europ<eus, and 

 C<esalpinia sepiaria, as determined by the balance. The plan 

 adopted was similar to that followed in the case of capsules like 

 those of Viola. The total loss of weight by drying of the 

 detached, full-grown green fruit was first ascertained and then 

 the loss of weight during parts of the process. Thus with 

 Viola capsules I found the loss of weight before and after 

 dehiscence began. With the legumes I checked the total loss 

 of weight during the drying of the green fruit by ascertaining 

 the average loss of weight after and before the pod had 

 blackened. By combined observation on these lines of the 

 detached fruit and of the fruit on the plant it is not difficult to 

 obtain an approximate result. With Vicia and Ulex the final 

 loss of water in the closing stage of the dehiscence immediately 

 resulting in the ekstic opening of the pod was determined by 

 placing the darkened or blackened, nearly dry pods, under a 

 glass in the sun, when they would all dehisce in an hour, and the 

 weights before and after the experiment were then compared. 



The results given for the three typical legumes in the 

 table below are closely similar. We there see that the full- 

 grown moist pod on the plant loses on the average 59 per 

 cent, of its weight before dehiscence occurs, and that the 

 subsequent loss of weight is small, the total loss in drying 

 amounting to about 62 per cent. 



TABLE ILLUSTRATING THE STAGE IN THE DRYING PROCESS AT 

 WHICH THE DEHISCENCE OF LEGUMINOUS PODS OCCURS. 



