FIELD AND LABORATORY EXERCISES 21 



seed coat or the seed case may be resistant to moisture. (3) The 

 place of storage of seed if very dry or very cold may hold the life 

 of the seed much longer. Grains sowed in very dry soil in an arid 

 region may live for several months without germinating. When 

 the next rain comes germination may follow quickly. Stories 

 are often told of seed being found in cases with Egyptian mummies, 

 which would germinate after many centuries. These stories are 

 not duly authenticated, but such conditions would be very favor- 

 able because of the absence of moisture. 



FIELD AND LABORATORY EXERCISES 



1. Study the flowers of different plants, and find some provided with 

 pistils, some with stamens and others with both organs. 



2. Determine what the effect would be of having only pistillate plants in 

 a strawberry bed. 



3. Study pollen of various flowers. This may be done with or without a 

 compound microscope. Decide whether the supply of pollen is abundant or 

 scarce with various cultivated plants that may be available. Determine 

 what flowers have light, dry pollen, which could be scattered by the wind, 

 and what ones have waxy or sticky pollen which would be carried chiefly 

 by insects. 



4. From Pistil to Seed. If possible, examine a certain kind of plant, tor 

 example, peas or beans, in the different stages of development of the seeds 

 (Figs. 13, 14 and 15). Begin with the first pollination and early development 

 of the embryonic seeds, and trace them toward maturity. 



5. Parts of Seeds. Study the parts of mature seeds, including 'those with 

 two seed leaves, as the bean, and including those of the monocotyledonous 

 type, as corn. The seeds are more easily examined if they have been soaked 

 a few hours in advance. 



QUESTIONS 



1. What are the organs of a flower essential for the production of seed? 



2. Of what use is the floral envelope? 



3. How may imperfect flowers produce seed? 



4. Describe the pollination and fertilization of a perfect flower. Of the corn 



plant. Of a pistillate strawberry. 



5. What are the characteristics of wind-pollinated flowers? 



6. Give the characteristics of flowers pollinated' by means of insects. 



7. Mention the conditions which influence the longevity of seeds. 



References. United States Farmers' Bulletin 195, Annual Flowering 

 Plants. Cornell Bulletins: 320 and 342, Sweet Pea Studies, III and IV. 



