52 FRUITS AND THEIR USES 



Formation of Seeds. — Each seed has been formed as a direct 

 result of the fertilization of the egg cell {contained in the embryo sac 

 of the ovule) by a sperm cell of the pollen tube. 



Seed Dispersal.! — If you will go out any fall afternoon into 

 the fields, a city park, or even a vacant lot, you can hardly es- 

 cape seeing how seeds are scattered by the parent plants and trees. 

 Several hundred little seedling trees may often be counted 

 under the shade of a single maple or oak tree. But nearly all 

 these young trees are doomed to die, because of the overshading 

 and crowding. Plants, like animals, are dependent upon their 



Young cedars around parent tree. Photographed by Overton. 



surroundings for food and air. They need light even more than 

 animals need it, because the soil directly under the shade of the 

 old tree gives only raw food material to the plants, and they must 

 have sunlight in order to make food. This overcrowding is seen 

 in the garden where young beets or lettuce are growing. The 

 gardener assists nature by thinning out the young plants so that 

 they may not be handicapped in their battle for life in the 

 garden by an insufficient supply of air, light, and food. 



' At this point a field trip may well be taken with a view to finding out how 

 the common fall weeds scatter their seeds. Fruits and seeds obtained upon this 

 trip will make a basis for laboratory work on the adaptations of seed and fruit for 

 dispersal. 



