56 



FRUITS AND THEIR USES 



Darwin, raised eighty-two plants from seeds thus carried by a 

 bird. It is probable that by means of birds and water most of 

 the vegetation has come into existence on the newly formed coral 

 islands of the Pacific Ocean. 



Some Other Forms of Fruits and their Method of Dispersal. Dry 

 fruits which do not split open to allow of the escape of their seeds are 



known as indehiscent fruits. Some are known as 



grains. Such are corn, wheat, oats, etc. A grain 

 is simply a one-seeded fruit in which the wall of 

 the ovary has grown so closely to that of the seed 

 that they cannot be separated. Such fruits are 

 usually small and numerous, having a thin outer 

 wall. The seed may easily germinate under favor- 

 able conditions. Other indehiscent fruits are nuts, 

 one-seeded fruits with usually hard outer covering, 

 the so-called key fruits of ,the maples or ash, and 

 many others. Some indehiscent fruits are light 

 and carried by the wind ; others are extremely 

 numerous and may be scattered by animals. The 

 key fruits depend upon the wind, while nuts are 

 often carried away, buried, and forgotten by blue 

 jays and squirrels, and thus obtain a new foothold. 



Large Numbers 

 of Seeds. Plants 

 which do not have 

 especial means for 



rip- 



Key fruit of maple. 



Grain ; spikes of 



ened flowers. 



means 



scattering then* seeds may make up for this 



by producing a large number of seeds and 



holding them in podlike fruits which are 



easily shaken by the wind. The Jimson 



weed is a familiar example of such a plant. 



Each capsule of Jimson weed contains from four hundred to six hundred 



seeds, depending upon its size. If all of these seeds develop, the whole 



earth would soon be covered with 



Jimson weed, to the exclusion of 

 all other forms of plant life. 

 That this is not the case is due 

 to the fact that only those seeds 

 which are advantageously placed 

 can develop ; the others will, for 

 various reasons (lack of moisture 

 to start the young seed on its 

 way, poor soil, lack of air or sunlight, overcrowding), fail to germi- 

 nate. 



The acorn, a nut in which the involucre 

 partly covers the fruit. 



