238 MANUAL OF BOTANY 



not ripen. But there are many exceptions to this ; thus, the 

 Bananas and many Oranges and Grapes produce no seeds, but the 

 pericarp is nevertheless fully developed ; and in Plantains and the 

 Bread-fruit the pericarps develop most extensively, and become 

 best adapted for food, when the seeds are chiefly or entirely 

 abortive. Generally speaking, however, the development of the 

 seeds and pericarp proceeds together after th^j process of ferti- 

 lisation has been effected, and only then can perfect frvAt be 

 formed ; for although in common language we apply the term 

 fruit. in those instances where no seeds are produced, yet strictly 

 speaking such are not fully formed fruits, but only enlarged and 

 swollen pericarps. 



Having now alluded to the seeds as a component part of the 

 perfect fruit, we must leave their particular examination till later, 

 and proceed to the description of the pericarp. 



Pericarp. — In the majority of fruits the pericarp consists 

 simply of the walls of the ovary in a modified state ; but, when 



Fig. 506. 



Ficj. 506. Foliaoeous bladdery legume of the Bladder Seiina (Colnlei 

 iirborescens). 



the calyx or receptacle is adherent, it necessarily presents a more 

 complicated structure. The pericarp sometimes exhibits three 

 laj'ers or regions {fig. 534), an external, called the epicarp or 

 exocarp, ep ; a middle, the mesoca/rp, ml ; and an inner, the 

 endocarp, en. If the middle layer becomes fleshy or succulent, 

 it is then termed the sarcocaip ; the inner layer in some fruits 

 becomes very hard, and is then called the stone or putamen. 



In some cases the pericarp clearly indicates its homology with 

 a leaf-blade by remaining in a condition not very dissimilar to 

 that part of a leaf folded inwards and united by its margins, 

 as in the Bladder Senna {fig. 506) ; such a fruit is described as 

 foliaceous or leafy. 



These modifications of the pericarp may with advantage 

 be illustrated by a few examples taken from weU-known 

 fruits. In the Peach, Apricot, Cherry, Plum, and most other 

 drupaceous fruits, the separable skin is the epicarp ; the pulpy 

 part, which is eaten, the mesocarp or sarcocai-p ; and the 



