THE ORCHIS FAMILY. 177 



1. Compare the flower throughout with that of the lily 



(or Trillium) previously studied, endeavoring to 

 ascertain the character and extent of its modifi- 

 cations. 

 a. How does the ovary compare with that of the 

 lily as regards adnation of the floral envel- 

 opes? 

 h. In what parts of the flower has coalescence oc- 

 curred ? 



c. Has suppression of any parts taken place ? 



d. Point out the most striking modifications of 

 form.i 



2. Construct a diagram and compare with that of the 



lily.2 



NoiE. — The student cannot hope to understand all of this at 

 once. The distance between the lily and the lady's-slipper is too 

 great to be bridged by a single effort of the imagination. Let him 

 do his best with the flower itself, then read the references, then lay 

 the whole matter aside, and return to it again after other representa- 

 tives of the family have been studied. 



III. The striking modifications of the flower of Cypri- 

 pedium are correlated with the visits of insects on which 

 it is dependent for fertilization. 



1. There are certain peculiarities likely to prove attrac- 



tive to insect visitors. Enumerate these. 



2. Assuming that an insect, a bee for example, is about 



to pass into the interior of the labellum, where 

 would it be likely to enter ? Would it probably 

 pass out by the same opening ? 



3. Examine carefully the structural peculiarities of the 



lip. Find where the tissue is thinnest, and accord- 



1 Cf. Gray, Structural Botany, p. 179 et seq. 



^ Cf. Goodale, Wild Flowers of America, p. 86 ; Darwin, Fertilization 

 of Orchids, pp. 234-246. 



