BIOLOGY OF HIGHER SEED PLANTS 65 



3. Draw the entire flower as it appears on the side from 



which the parts have been removed. Indicate accu- 

 rately in the drawing the form and relative position of 

 the floral parts on the floral axis. 



a. Study the text and Figs. 215 and 84 and name the 

 parts of the flower sketched above. 



4. The essential organs of the flower. 



a. Anthers and pollen. Observe carefully with a hand 



lens and low power the dehiscence of the anther. 

 Does the anther sac open crosswise or lengthwise to 

 shed the pollen? Do you see the dustlike pollen 

 grains issuing from the slit, or dehiscence line, of 

 the anther? How many anther sacs are there in 

 one anther? Draw a stamen greatly magnified to 

 show the mode of dehiscence of the anther sac. 



b. Pollen. Dust some pollen on a slide and study its 



form and structure. Is the pollen grain a cell ? Is 

 its wall smooth or rough ? Can you see any cell 

 contents? Draw the pollen, exterior view, as it 

 appears to you in your specimen. 



c. The pistil 



(1) Observe the external parts of the pistil and note 



their form and structure. Observe the stigma 

 carefully. Is it adapted to the reception and 

 retention of pollen ? Draw a pistil, including an 

 enlarged view of the stigmatic surface, and name 

 all its parts. 



(2) Cut a transverse section of the upper and middle 



portions of the ovary. Cut also a section through 

 the style, if one exists. How does the ovary 

 differ in structure at the different levels at which 

 you have cut it ? How is the wall of the ovary 

 modified in the median, or middle, section of the 



