EXERCISE 104 

 THE STAMEN OF A FLOWERING PLANT (ANGIOSPERM) 



Materials. Stamens from flower of lily or similar plant, but 

 stamens from almost any flower can be used; slides showing cross 

 sections of anthers with pollen. 



Directions for work. The structure of the vegetative parts of 

 the flowering plants (properly called angiosperms) has been 

 studied previously (Exercises 1-74), as is also true of some 

 of the facts about the flowers. Only a few of the details of 

 reproduction will be presented here. The gametophytes of 

 angiosperms are more reduced than those of gymnosperms. 



Examine a stamen which has not shed its pollen and note 

 the pollen sacs (sporangia). How many are there? If the 

 anther is cut across with a sharp knife, the relation of parts 

 may be the more readily seen ; use a lens. 



If you have slides with cross sections of anthers, examine 

 them with the low power of the microscope. Make a diagram 

 showing the shape and relation of parts. 



Place some of the pollen grains on a slide without water 

 or a cover glass. Examine with the low power of the micro- 

 scope. If you will set the microscope in a brightly lighted 

 place and turn the mirror so that no light is reflected from 

 below, the pollen grains will be seen in their natural colors 

 against a dark background. 



References 



BERGEN and CALDWELL. Practical Botany, pp. 110, 111. 

 BERGEN and CALDWELL. Introduction to Botany, pp. 129, 299. 



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