83 



The Ipontoea testigridis L. has cleistogamous flowers. 

 This is said to be true also of some members of the genus. 

 CuSCuta. The /. batatas, or Sweet Potato, seldom flowers. 

 The members of this order are adapted to a 

 various class of visitors. The large-flowered 

 species of Datura are adapted to Sphingidae and especially 

 to the humming bird. In Solarium tuberosum and S. nigrum 

 the flowers do not secrete nectar but are visited solely for 

 their pollen. In S tuberosum the five anthers meet to form a 

 cone and surr )und the style. The anthers begin to dehisce 

 at their apex and when touciied the pollen falls out. Mr. 

 Robertson has observed females of Bombus americanorum col- 

 lecting the pollen. 



Datura Stramor),ium. The Jamestown Weed is a tall 

 (Oarse weed with a white corolla about three inches long and 



FIG. 33. 

 Fi^. 33, II. Datura flowpr visited by humming bird; three-fourths natural 

 size. Left hand figure. Heinthrijc nurita^ three-fourths natural eize. Right 

 hand figure. Helmctinus enrnutun, three-fourths natural size. I. Sword beak 

 DocimasteH ensifer. (After Brehm. from Behrens' text book.) 



