August, '12] RIXFORD: FIG FRUCTIFICATIOX 3i9 



FRUCTIFICATION OF THE FIG BY BLASTOPHAGA^ 



By G. P. RiXFORD, U. S. Department of Agriculture, Bureau of Plant Industry 



The subject of this paper is both botanical and entomological and 

 to make it clear, it is necessary to mention some of the botanical 

 characteristics of the fig. 



Botanists are now generally agreed in the acceptance of the ideas 

 of Linneus and others that the caprifig is the staminate form and the 

 Smyrna and all the common figs in cultivation the pistilate form of a 

 dioecious species. Hegardt reached this conclusion as early as 1844 

 and this view is now generally accepted. 



The fruit of the fig tree is not a fruit in the sense in which we regard 

 the apple, peach, etc., but is what is known to botanists as a receptacle, 

 upon the inner surface of which are arranged hundreds of unisexual 

 flowers. At the apex of the receptacle is an opening which in the 

 young fruit is closed by a number of scales or imbricated bracts. 

 The blossoms of the fig tree are therefore never seen except by open- 

 ing the fig. The flowers thus being effectually cut off from the outer 

 world, there is no way by which the pollen from the male flowers can 

 reach the female flowers, except by the assistance of some outside 

 agency. In this case the medium of conveyance is the female Blas- 

 tophaga grossorum. 



Crops of the Fig Tree. All the female fig trees, both of the Smyrna 

 class, the fruit of which never matures without pollination, and the 

 other large class which does not require pollination, have two well 

 defined crops. The first pushes from the old wood and is the first 

 to appear in spring, ripening in July and August and in the south 

 of Europe are called Brebas,^gwes fleurs or figues d'ete. The next, 

 which is the main crop, called in France figues d'automne, spring from 

 the axils of the leaves of the new wood and ripen in summer and fall. 



The crops of the male or capri tree are two well defined and a third 

 which is in doubt l)y some authorities. To these for convenience the 

 Neapolitan names, mamme, profichi and mammoni have been applied. 

 The first or mamme crop forms in late summer on- the wood of the 

 current season and the Blastophaga from the preceeding mammoni 

 oviposits in them when they have reached the size of filberts. By 

 December these are the size of small walnuts and change but little 

 during winter. The insect hibernates in thern in the larval condition 

 and will endure a temperature of 20 degrees without injury. As 



I Read at the meeting of the Pacific Association of Scientific Societies held at Berke- 

 ley March 31, 1911. 



