ORIGIN AND DEVELOPMENT 01 SOME COMMOA FRUITS. 



The fruit of the lemon and orange 

 are also derived from the pistil alone : 

 but whereas in the grape, cherry, peach 

 and plum it is the wall of the pistil or 

 ovary which becomes the succulent part, 

 in the lemon and orange the ovary wall 

 forms only the yellow skin, while the 

 juicy flesh is formed by a mass of hairs 

 which fill up the cavity of the ovary. 



The apple blossom is illustrated in 



Fig. 1524.— The Apple (Pirus mains). A, flower; 

 B, flower in section ; C, flower in section with 

 corolla removed ; r, the axis or stem which 

 develops into the fruit ; D, fruit in longi- 

 tudinal section, showing persistent calyx k, 

 wall of ovary /, and vascular bundles <j. E, 

 fruit in cross section. 



Fig. 1524. If we look closely at the 

 sections of flowers as shown at B and C, 

 we shall note two principal variations 

 from the structure of the cherry flower. 

 The apple instead of one pistil as in the 

 cherry has usually five ; and the pistils 

 instead of sitting freely in the bottom of 

 the cup of the stem as in the cherry, are 

 fused wtth the cup of the stem in the ap- 

 ple. As the fruit begins to develop after 

 fertilization, the stem-cup, as well as the 

 pistils, enlarges, carrying the rest of the 

 flower on the rim of the cup for a short 

 time ; soon the corolla, the stamens and 

 the upper part of the pistils fall off, but 

 the calyx remains even upon the ripe 

 fruit. 



Of a quite similar origin to the apple 

 are the pear and quince. The fruit of 

 the apple, pear and quince is therefore 

 a swollen stem or axis enclosing the base 



of the pistil, thus differing widely from 

 the fruits previously considered. 



Currants, ^huckleberries, gooseberries 

 cranberries, pumpkins, squashes, melons 

 and bananas have a similar origin to the 

 apple ; for in the flower, their pistil-base 

 is fused with the cup of the stem, and as 

 the fruit develops both stem-cup and 

 pistil-base enlarge together. There is, 

 however, this difference between the 

 fruits last named and those of the apple, 

 pear and quince ; in the latter group the 

 edible part is all or nearly all stem ; 

 while in the former group, the stem 

 part is but a thin covering over the out- 

 side, the edible part being mostly pistil. 



The flowers of the blackberry and 

 raspberry have, as shown in Fig. 1525, 

 a single circle of calyx leaves, a single 

 circle of corolla leaves, but several cir- 

 cles of stamens and pistils. By looking 

 at B, Fig. 1525, it will be seen that the 

 cal>T(, corolla and stamens, just as in 

 the cherry and apple, arise from the 

 rim of a stem-cup, a deep cup in the 

 cherry and a shallow cup in the black- 



FiG. 1525.— European Wild Blackberry. (Rn- 

 bus fruticosus). A, a flowering branch* IB, 

 flowerin longitudinal sections ; C, branch^with 

 fruit ; p corolla and e caljrx. 



berry. This cup in the raspberry and 

 blackberry has rising from its bottom 

 a solid dome, on whose sides the pistils 

 are arranged. This dome is a part of 

 the stem. 



The flower of the strawberry is in 

 every way quite similar to that of the 



55 



