THE ANGIOSPERMAE 



1327 



pollen it may have on its head will be deposited on it. After about two 

 days in this state, the style withdraws the stigmatic tip from the mouth of the 

 flower and the filaments of the stamens straighten, bringing the anthers into 

 the open mouth of the corolla. Here they dehisce and a wasp entering the 

 flower at this stage will become liberally dusted on the head with pollen. 

 Although the stigma moves away from the opening, it does not lose its 

 receptive power, so that, if cross-pollination fails, it may be self-pollinated 

 by pollen which falls from the anthers above it. Wasps, unlike bees, gener- 

 ally start with the young flowers at the top of an inflorescence and work 

 downwards and hence the chances of crossing between different plants are 

 increased. It has also been observed that, towards the end of the season, 

 wasps cease to visit the flowers and at that time the remaining flowers may be 

 visited by both Hive and Humble Bees. 



The great genus Ficiis has about 600 species distributed around the 

 world in the warm zones and it appears to be pollinated everywhere by 

 small chalcid wasps of several different genera. A single species of wasp, 

 such as Blastophaga brasiliensis, may pollinate a number of Fig species. 

 Others are limited to one plant species. Among the latter is Blastophaga 

 grossonmi, which pollinates the edible Fig of Southern Europe. 



The Cultivated Fig, Ficiis carica, is dependent upon this gall wasp for the 

 production of seed, although edible fruits may be formed without pollina- 

 tion. These fruits are compound structures (syconia) composed of fleshy, 

 pear-shaped inflorescence axes, which are hollow inside and open by a con- 

 stricted apical pore surrounded 

 by small scales (see Fig. 1404, 

 p. 1543). Lining the inside are 

 numerous unisexual flowers. 



The Wild Fig produces three 

 distinct types of "fruits " each 

 year which differ both in the 

 kind of flowers which they con- 

 tain and the degree of fleshiness 

 of the fruit. 



I. The Profichi. In Italy, 

 these fruits are produced during 

 February. They contain male 

 flowers which are formed chiefly 

 around the apical pore and 

 abortive female " gall flowers " 

 which develop lower down, the 

 proportion of male to female 

 flowers being about i to 8. The 

 " gall flower" has a rudimentary 

 ovary, incapable of producing seed and a short style with an abortive stigma 

 and an open canal leading into the ovary (Fig. 1241). It has no function 

 other than its association with the wasps. 

 K 



Fig. 1241. — Ficiis carica. A, Male flower. B, Fer- 

 tile female flower. C, Female gall flower. D, 

 Blastophaga wasp. (A and D after Kertier. 

 B and C, after Condit.) 



