166 STUDY OF COMMON PLANTS. 



ingly well-defined species. Record what you have ob- 

 served regarding the habitat and duration of the plant, 

 and any other characters not mentioned above. Do its 

 habits indicate that it is indigenous ? 



Iiiflorescence and Flowers. 



I. In studying the plant, remove the spathe, observing 

 meantime whether any special devices exist for the attrac- 

 tion of visitors. 



II. Examine the spadix carefully, comparing it in plants 

 of different ages. The flowers are said to be proterogynous. 

 Is the statement confirmed by your observation? 



III. Satisfy yourself by a further comparison of speci- 

 mens whether self-fertilization is possible.^ 



IV. Examine the individual flowers, making sections 

 for this purpose that will show their structure and rela- 

 tion to the axis of inflorescence. Are all the flowers 

 perfect? How do the stamens of older flowers differ from 

 those less developed? 



V. Construct a diagram showing the plan of the flower. 



CALLA. Richardia Africana, Kunth. 



Compare the inflorescence and flowers of the cultivated 

 calla with those of the preceding species. Note 



I. The color and form of the spathe. 



II. The structure of the flowers. Are they perfect? 

 Are there any floral envelopes ? 



III. How do those of the upper part of the spadix com- 

 pare with those of the lower portion ? 



1 Cf. Trelease, Am. Nat., September, 1879. 



