Ch. VII, 2] 



MORPHOLOGY OF FRUITS 



351 



single carpel from which each fruit is developed. In the 

 fleshy fruits of the Apple and Pear type, the receptacle grows 

 up and incloses the carpels (the core), forming a type called 

 the POME, the receptacular nature of 

 which is further attested by the obvious 

 remnants of persistent sepals. In some 

 of the largest gourd fruits, like the 

 Pumpkin and Squash, the outer wall is 

 hard and only the inner part becomes 

 edible, while in the related Watermelon 

 it is chiefly the placentae which form the 

 pulp, as is likewise true in Tomato and 

 Cucumber. As to the method of protec- 

 tion of the seeds in large fruits like the 

 Apple, Watermelon, and Orange, that 

 will presently be mentioned. 



In the fruits just described the pulp results from the spe- 

 cialized ripening of carpel, or receptacular ovarian ivall, or 

 ■placenta ; Ijut it may develop from other parts also. Thus 

 in the Strawberry the edible part of the fruit is wholly the 

 receptacle, which bears the manj^ seed-like 

 akene fruits. In the Wintergreen berry 

 the pulp is largely calyx: in the Yew 

 berries it is an extra seed coat (for Yews 

 have no ovaries), called an aril. In the 

 Orange, which is a kind of huge berry 

 with a separable skin, the pulp is con- 

 stituted from hair-like structures developed 

 from the inner walls of the carpels. 



In considering the various morphological 

 origins of the pulp one cannot but ask why 

 one plant forms it in one way and another 

 so differently. As to this we have little 

 exact knowledge ; but circumstantial evidence indicates 

 that here, as elsewhere, evolution moves along lines of least 

 resistance, the pulp in any given case being made from 



Fig. 246. — Drupe 

 of Cherry. The stone 

 is cross-lined. (From 

 Figurier.) 



