CHAPTER X. 



FBUITS AND SEEDS. 



277. How Fruits are Formed. The influence of fertili- 

 sation extends from the developing seeds to the surrounding 

 parts, causing a renewal of active growth not only in the car- 

 pels, but often in other parts of the flower as well. Usually, 

 however, the stamens and corolla persist for a shorter time 

 than they would have done had not fertilisation occurred. 



The ultimate result of fertilisation is the formation of a 

 fruit. The simplest definition of a fruit is that it consists of 

 the parts of a single flower which persist and grow after 

 fertilisation. This definition covers most fruits, which may be 

 divided into simple and aggregate. A. simple fruit is formed 

 from one free carpel, as in the Bean, or from several united 

 carpels (syncarpous pistil), as in the Poppy. An aggregate 

 fruit is formed from several free carpels, as in Buttercup and 

 Blackberry. The wall of the ovary becomes the pericarp or 

 fruit- wall, which may, as the fruit ripens, either remain soft 

 and fleshy or become dry and hard. 



Whether the fruit is dry or fleshy depends on the amount 

 of water it contains when ripe. Dry fruits which contain 

 several seeds usually open so as to set the seeds free, the 

 pericarp breaking apart to form an opening. Some dry, many- 

 seeded fruits, however, split into pieces, each containing a 

 single seed. These two types are distinguished as (1) Open- 

 ing or Capsular fruits ; (2) Splitting or Separating fruits. 

 Dry one-seeded fruits, and practically all fleshy fruits, re- 

 main closed, and the seeds escape by the decay of the 

 pericarp, or the latter may only be broken when the seed 

 germinates. This third type may be called (3) Closed or 

 Indehiscent fruits. Indehiscent fruits may be either dry, in 

 which case they are usually one- seeded, or flesh j. 



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