. THE DIFFERENTIATION OF FLOWER-BUDS 49 



seeded (or at most two-seeded), in the ripening of which the 

 outer portion of the ovary (pericarp) often becomes fleshy or 

 pulpy as in the peach, plum and cherry, or thinner and hull- 

 like as in the almond, and the inner portion of the ovary 

 becomes stony or crustaceous; hence the term "stone-fruits." 



The raspberry consists of an aggregate of drupelets which 

 develop about a thickened portion of the torus but from 

 which they readily separate as they mature. The drupelets 

 may adhere closely after being harvested or they may have 

 a tendency to crumble apart, depending on the variety. 



The blackberry is likewise an aggregate of drupelets but 

 it differs from the raspberry in that the drupelets adhere to 

 the fleshy part of the torus and the entire mass usually 

 separates from the calyx and flattened portion of the torus 

 when mature. The loganberry is the same morphologically 

 as the blackberry. 



The strawberry, like the fruits just described, is not a 

 true berry. It consists of a much thickened fleshy and edible 

 portion of the torus or receptacle, upon which are located 

 the true carpels which are hard one-seeded achenes scattered 

 over the surface of the receptacle. They may be somewhat 

 depressed or slightly raised and the styles may be deciduous 

 or may persist and give the surface a more or less roughened 

 surface. The persistent calyx is leafy and prominent. 



A berry proper is an indehiscent fruit fleshy throughout. 

 There is considerable variation in the details of the con- 

 struction of the berry. Some of them, such as the blueberry, 

 huckleberry, cranberry, and banana, are inferior ovaries, 

 whereas others, such as the tomato, orange, lemon, and other 

 citrus fruits, are superior ovaries. 



In the nut the ovary is hardened into a "shell " and it is fre- 

 quently covered or surrounded by a husk which consists of the 

 perianth of the flower or bracts which are derived from the 

 receptacle. The edible portion is composed of the embryo. 



