224 STUDY OF COMMON PLANTS. 



Flower. 



I. Study the plan of the flower. What is the original 

 numerical plan as indicated by the floral envelopes? Is 

 this plan apparent in the androecium ? In the gynsecium ? 

 How many perfectly developed stamens are there? See 

 if you can find traces of another one. If so, how does it 

 compare with the rest? How many carpels compose the 

 pistil? On what evidence is this determined? 



II. Construct a diagram of the flower. If you find a 

 trace of a fifth stamen, mark its place with an x. 



III. Examine a transverse section of an ovary from 

 which the corolla has fallen, and notice the arrangement 

 of the ovules, and the position and form of the placentae. 

 In a still older ovary observe the form and structure of 

 a young seed. 



IV. When the capsules are ripe study their structure 

 and mode of dehiscence. 



V. Study carefully the adaptations for securing fertili- 

 zation by the agency of insects. Begin with the corolla 

 and note 



1. Its bilabiate form. 



2. The conspicuous palate and its color as compared 



with the rest of the corolla. 



3. The spur. Where is the nectar? Is it easily acces- 



sible to all sorts of visitors? Imitate the action 

 of a bee in gathering honey. Depress the lower 

 lip by pushing down the palate with a needle. 

 Are there any path-pointers ? Notice the position 

 of anthers and stigma. 



If possible, watch a bee visiting a plant, and observe 

 the mutual relations of insect and flower. 



