186 FLOWERS 



Sketch the cone, showing the rows of scales as they stand. 



Remove a scale and draw the upper and under views. 

 Look for ovules (two small elevations near the base of a 

 scale). Do you detect any means by which the pollen grains 

 could be caught? Do you find anything corresponding to 

 petals or sepals here ? pistils ? 



Examine an older cone and determine the fate of these 

 ovules. 



Dip an old cone in water. What happens? Dry it out. 

 What happens? What has the ability to open and close 

 to do with dispersal of the seeds? 



Note. On account of the difficulty of obtaining the staminate 

 flowers of pine trees the following plants may be studied equally 

 well for work on imperfect flowers : any other cone-bearing plant, 

 oak, willow, walnut, poplar, hickory, or chestnut. 



165. POLLEN (optional) 



Object. To study pollen. 



Method. (a) Mount dry a few grains of pollen by shak- 

 ing a ripe stamen over a microscope slide, and examine them 

 with a low power. 



Sketch a few grains as they lie scattered over the field 

 in various positions. 



To some fresh pollen on a microscope slide, add a drop of 

 water. What effect does it have on the pollen grains ? 



Examine as many kinds of pollen as possible, especially 

 that of dandelion, rose, tulip, pine, corn, milkweed, and 

 evening primrose, where these can be had. 



Which have large grains? small grains? dry grains? 

 moist grains ? Which show special means of flight ? Which 

 have special means for sticking to insects? What colors 

 are most common in pollen? 



