86 RECIPROCAL NUTRITIVE DISJUNCTIVE SYMBIOSIS 



ring of hairs withers and the insects are liberated and are free to fly 

 to another flower. 



The Jack-in-the-pulpit (Arisxma triphyllum) which belongs to the 

 same family as the .4mm, is also somewhat of a prison flower. This 

 species is dioecious and the staminate plants mature a little in ad- 

 vance of the pistillate. The spathes are extremely smooth and 

 slippery on the inner side. The flies are very likely to visit a stam- 

 inate inflorescence first and once inside the spathe they are unable to 

 climb up the smooth walls or the equally smooth spadix. As soon 

 as the spathe begins to wither, however, it becomes less smooth and 

 the flies escape and may chance then to visit a pistillate plant and so 



Fig. 35.— Skunk cabbage (Sytnplocarpus foetid us). A fly flower. 



eftect pollination. In the pistillate inflorescence they are again 

 imprisoned until the spathe begins to wither. This does not take 

 place so promptly as in the case of the staminate plant and often 

 the insects perish before they are liberated. 



53. Pollination of the Fig.— One of the strangest of the known 

 cases of symbiosis between flowers and insects is that of the com- 

 mercial fig and the wasps of the genus Blastophaga which pollinate it. 

 The flowers of the fig are produced in composite inflorescences called 

 syconia. A syconium consists of a fleshy receptacle which has de- 

 veloped into a hollow structure with a very small orifice at the upper 

 end. The numerous flowers are arranged on the inner side, which is 

 the morphological upper side, of the receptacle. The flowers are 



