STRUCTURE OF FRUITS 365 



In popular language a fruit is a fleshy envelope which 

 can be eaten enclosing seeds, but the edible part is not 

 necessarily formed from the pericarp. For instance, 

 the fleshy part of an apple, a fig, or a pineapple, is not 

 pericarp at all. The botanical conception of a " true " 

 fruit (i.e. the structure formed from the carpels alone 

 by the time the seeds are ripe) is both wider and narrower 

 than the popular conception. Thus it includes the 

 bean pod and the coconut, while it excludes all but 

 the " pips " of a fig, and the core of an apple. We 

 may, however, conveniently include in the general term 

 " fruit " all the structures enclosing the ripe seeds, 

 whether derived from pericarp or not. 



The only way to understand the nature of the parts 

 of a fruit in this wide sense is to follow their develop- 

 ment from the flower. It is especially the receptacle 

 that very frequently takes part in the structure of the 

 fruit. This is necessarily the case in all fruits formed 

 from " inferior " ovaries (p. 354), because the wall of the 

 receptacle is here fused with the wall of the carpels. 

 The wall of the receptacle and the wall of the carpel 

 may together form quite a thin membrane, but, on the 

 other hand, one or other or both may swell up and 

 become fleshy in the fruit. 



The cherry, the rose and the apple belong to the 

 same family (Rosaceae, the rose family), and they illus- 

 trate these differences very well. The cherry, as we 

 have already seen, has a cup-shaped receptacle with 

 a single free carpel at the base of the cup. It is the 

 ovary of the carpel alone which forms the cherry. The 

 receptacle does not grow after fertilisation, and is soon 

 flattened out by the great growth of the young fruit — 

 it can still be seen as a little disc at the base of the cherry 

 where the stalk joins the fruit. The wall of the carpel 



