THE FRUIT OF OPUNTIA FULGIDA. 25 



THE FRUIT: ITS STRUCTURE. PERSISTENCE. AND FATE. 

 NORMAL AND ABNORMAL. 



The fruit of Opuntia fidgida occurs, as we have seen, in ehisters of from a 

 dozen to a hundred or more depending from one vegetative joint or even, from 

 a single parent frnit (figs. 2, 3). The individual fruit may he globular in 

 form, or barrel-shaped, pear-shaped, or still more elongated and nearly cylin- 

 drical (figs. 3, 4, 7, 26, 28). It may have a diameter of from 20 to 35 mm. 

 and a length of from 25 to 65 mm. Its size differs with the plant and with 

 its position in the cluster. The terminal and younger fruits are usually 

 smaller, but sometimes those of any one growing-season seem small through- 

 out. The surface of the upper or terminal end of the fruit is formed by the 

 cork-covered scar left by the fall of the perianth and stamens. This scar is 

 decidedly concave when young, but with age it flattens out or, in some 

 cases, even bulges slightly at the center (figs. 3, 25, 28). The lateral sur- 

 face of the fruit when young has markedly developed tubercles, or mammil- 

 lae, each terminating in a leaf-scar and its accompanying areole (figs. 4, 17, 

 31, 32, 47). These tubercles become less prominent as the fruit grows 

 older and at last nearly disappear, though traces of them are seen in the 

 pentagonal or hexagonal form, in cross-section, of older fruits (figs. 3, 

 26, 43). 



The internal structure of the fruit is far more variable than that of the 

 exterior. It may have no seeds at all or it may contain anywhere from 1 ta 

 200 or more seeds. These seeds may all be shriveled, partially developed 

 rudiments, or from a few to most of them may possess normally matured 

 embryos. The number, condition, and structure of the seeds seem to show 

 no correlation with the external form of the fruit (figs. 25, 26, 28). 



The most striking peculiarities of the fruit of this Opuntia are, as 

 suggested above, its failure to ripen, its persistence on the plant, its long- 

 continued gi'owth, and finally its capacity for proliferation, whether left 

 attached to the parent plant or torn loose from it. 



THE FRUIT AT THE TIME OF ABSCISSION OF THE PERIANTH. 



With the dropping from the ovary of the stamens and perianth we have 

 left the earliest stage of the fruit proper. Externally, the fruit so formed is 

 a globular or obconical structure, with a very deep, funnel-like depression in 

 the top and from 15 to 40 strongly raised tubercles on its sides. Each of the 

 latter bears a leaf-scar and a more or less developed areole at its upper end, 

 which was mentioned in describing the ovary of the flowers. 



In internal structure this young fruit consists of the superficial epidermis, 

 which is soon continued over the leaf-scars and perianth-scars by a corky 

 periderm. Below the epidermis is the 4 or 5 layered hypodennis, consisting 

 of an outer layer of crystal-holding cells, and within this of 3 or 4 layers of 

 collencliymatously thickened cells, in which the cell-cavity is finally to be 

 nearly obliterated (figs. 71, 72). Within the hypodermis are the elabor- 



