398 



HUTCHINSON'S POPULAR BOTANY 



FIG. 489. NECTAR GLANDS. 



The first figure shows a gland at the base of the 



ovary in Veronica ; the second is part of a cherry 



leaf with two nectaries (H) at its base. 



flower might remain unvisited and would 

 probably never get fertilized, for the Fig 

 is protogynous. In fact, the two kinds of 

 Fig-tree caprificus and jicus, as the Italians 

 call them stand to each other in the 

 relation of male and female, being, broadly 

 speaking, the different sexes of the one 

 species, Ficus car lea ; and each appeals to 

 the-olfactory sense of insects with a distinct 

 purpose. Caprificus may be popularly 

 regarded as the "male tree" i.e. its 

 hypanthodia produce male flowers near 

 the opening (oatiole) and abortive female 

 flowers, known as gall-flowers, lower down. 

 Ficus is the " female tree " ; its inflorescences, which form the edible Fig r 

 contain only female flowers. 



Concerning these gall-flowers, some very remarkable facts are known. 

 " As the name indicates," says Kerner, " not fruits but galls are produced 

 from these modified female flowers, and this happens in the following 

 manner. There is a small wasp . . . Blastophaga grossorum, which lives 

 upon the Fig cultivated in the South of Europe. This insect passes into 

 the cavity of the inflorescence through the orifice, and there sinks its 

 ovipositor right down the style-canal of a flower and deposits an egg 

 close to the nucellus of the ovule. The white larva developed from the 

 egg increases rapidly in size and soon fills the entire ovary, whilst the ovule 

 perishes. The ovary has now become a gall. When the wasps are mature 

 they forsake the galls. The wingless males are the first to emerge, and they 



effect their escape through a hole which 

 they bite in the gall. The females 

 remain a little longer in the galls and 

 are there fertilized by the males. After- 

 wards they come out also, but only stay 

 a short 'time within the cavity of the 

 inflorescence, issuing from it as soon as. 

 possible into the open air. They crawl 

 up to the mouth of the inflorescence,, 

 and in doing so come into contact with 

 the pollen of the male flowers and get 

 dusted all over the body, head, thorax, 

 abdomen, legs, and wings. After squeez- 

 ing through between the scaly leaves 

 at the mouth of the inflorescence, and 

 having at last reached the outside, they 

 let their wings dry and then run off to- 



FIG. 490. NECTAR GLANDS. 



The dark spot (n) on each of the stipules of the Broad 

 Beao-is a nectar gland. 



