THE STRUCTURE OF FLOWERS, 55 



It is, however, the floral receptacle which is the 

 usual source of honey. In the Pluniba'go (Fig. 1) there 

 are five glands swelling up between the stamens ; and 

 if the flower be looked at from above, it will be seen 

 that there are five passages, down which the insect's 

 proboscis would go, directly over the glands. 



In Geranium there are also five little knob-like 

 glands (Fig. 41, 1.), of which one stands in front of each 

 sepal ; but in Pelargo'nium, of the same family, there is 

 a single honey -tube or nectary at the back of the flower 

 running down the pedicel, as described above (Fig. 12). 



In some flowers a complete thick ring within the 

 corolla completely surrounds the pistil. This is called 

 a Disc, and is characteristic of a large group of families 

 known as Discijiorce, of which, for example, Rhus 

 (Fig. 8) and the wilde Kastanien {Caloden dron) belong. 

 Again, of the Labiate family, Leondtis Leonu^rus ^ has a 

 thick, ring-like disc below the four-lobed ovary. It is 

 rather elevated on the anterior side, just where the 

 proboscis of an insect will reach it. 



The use of the receptacular tube is also to secrete 

 honey. Thus, where it is free from the pistil, its upper 

 or inner surface, as of the cup of the peach flower 

 (Fig. 9), has a thickening which secretes it. 



When the receptacular tube is adherent to the 

 ovary (Fig. 1), then it is usually the top of the ovary, 

 the only part of it exposed, or the base of the style 



* See figure under Lahiatx (IV.). 



