292 Journal of the Asiatic Society of Bengal [K.S., XIII, 1917.] 



Summary. 



1 . The flowers of the whole genus of Alysicarpus have a 

 strong explosive mechanism, which is set in action by the 

 sudden bending of the claws of the keel by the sun's action. 



2. In A. rugosus— one of the species with a glumaceous 



calyx— no explosion takes place without a visit from a particular 

 insect. 



3. The particular insect -visitor for this species is Nomia 

 oxybeloides. 



4. Unexploded flowers do not set fruits, though often a 

 few grains of pollen are seen attached to the stigma 



5. Nomia, on which A rugosus entirely depends for 

 fertilisation, are not found in sufficiently large" numbers, and 

 this evidently accounts for the plant putting forth one or two 

 flowers only daily so as to ensure the certainty of a good pro- 

 portion of them setting fruits. 



i 6 ' The narrowness below the apex and the cupular tip of 

 the keel are responsible for the pollen being thrown upwards 

 with force. fo r 



7. Since the pollen is strewn about, the insect is made to 



visit a large number of flowers, before it could get a good load 

 of pollen. & & 



8. The Mings being interlocked with the keel, the flowers 

 become quite inconspicuous soon after explosion, and it is a 

 help rendered by the plant to the insect to make the best use 

 ot its time. 



9. Nomia oxybeloides visits at one time only one or two 

 nowers m one plant, though many of then ma v be open. Thus 

 beitonogamy is prevented and Xenogamy ensured. 



IV. In A. vaginalis, with a small calyx, explosion takes 

 fore? Sp ° ntaneousI >' wi thout any insect -visit or any external 



11. Since the interlacing branches of many plants are 



oW If? n T ° ne auoth er and the inflorescences are seal so 

 dose that each one hardly gets an area of 1-6 square inches on 

 an average, and since the flowers by explosion could throw the 

 "J" t0 K f d u lsta nce of an inch, or an inch and a half. Xenogamy 

 is brought about without external agencies. 



