STUDIES OF SEED-PLANTS 217 



cherry and plum), or dry and hard (as in the so-called " seeds " 

 of sunflower and buckwheat). In other cases, as in bean pod 

 and poppy capsule, there are many seeds inside the structure 

 formed from the wall of the ovary (Fig. 63, C). 



Some fruits are more complex than the above in that they 

 include structures in addition to the pistil. For example, 

 the core only of an apple develops from the ovary, while the 

 outer edible fleshy part is formed by growth of the receptacle 

 which grows up and surrounds the ovary. 



Moreover, what is popularly termed a " fruit " may con- 

 tain several developed ovaries (botanically, fruits). For ex- 

 ample, the fleshy part of a strawberry is formed from the 

 receptacle of the flower, and the small hard grains (so-called 

 " seeds ") on the surface are each from a pistil (the straw- 

 berry flower has many pistils), and hence a strawberry is a 

 mass of aggregated fruits set on an edible receptacle. 



For purposes of study and comparison, it is most conven- 

 ient to group fruits under the following headings : (1) simple 

 dry fruits, (2) simple fleshy fruits, (3) stone-fruits, and (4) 

 complex fruits. The word " simple " is used to mean a fruit 

 developed from pistil only, while " complex " is applied to 

 fruits developed from ovary surrounded by overgrown recep- 

 tacle, as in case of the apple. 



213. Simple Dry Fruits. Under this heading are in- 

 cluded the fruits which are developed from one ovary, and 

 in which the ovary-wall becomes hardened and dry when 

 mature. There may be in the ovary one ovule forming one 

 seed, or many ovules resulting in a many-seeded fruit. Also 

 there may be many pistils in a flower, and each form a fruit 

 (e.g., buttercup). Examples of dry fruits are akenes, grains, 

 nuts, pods, follicles, and capsules. 



Akene. A simple dry unopening fruit (like that of the 

 sunflower, buttercup, buckwheat, dock, bur-marigold) con- 

 taining but a single seed, is an akene. As in the case of the 

 sunflower and buckwheat, these simple fruits are commonly 



