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TEXTBOOK OF BOTANY 



natural conditions remains viable but a short time, usually not more than 

 a day or two. Under artificial conditions and proper drying it may be 

 kept alive for a few weeks or even months. It has been reported that 

 the pollen of date palms has been kept viable from two to eighteen years. 

 The number of pollen grains produced by a single plant is often 

 prodigious. A single corn plant, for example, may have as many as 50 

 million pollen grains. The number of seeds on an ear produced by this 

 same corn plant will rarely exceed 1000. 



The importance of incidental pollination brought about by bees, 

 wasps, Hies, and other insects that use pollen and nectar as a source of 

 food has been known for years ( Fig. 171 ) . The current statements that 



/ 



WASP BEARING POLLEN 



GRAINS BRINGS THEM 



IN CONTACT WITH 



THE STIGMA 



ABSCiSED /- 

 FUDRAL CUP ■• 



THIRD DAY 



FOURTH DAY 



FRUIT 



Fig. 171. Successive stages in the development of the flower, polhnation, and growth 

 of fruit in the common figwort. From W. Hamilton Gibson. 



insects are more likely to visit flowers having a striking color, a special 

 appearance, or a large size have little if any foundation in fact. Such 

 matters cannot be discussed with certainty until more experimental data 



