213 

 Pollination of Campanula Americana and Other Plants. 



Moses N. Elrod. 



Cdiiiixniiihi Americana L. is markedly proterandrous. In the bud the 

 aiitlu'is are in contact witli tlie pilose tAAO-thirds of the style and dis- 

 charge their pollen introrsely before the corolla opens. As the flower bud 

 opens the filaments wither beyond their more persistent bases. In the 

 meantime the style grows rapidly in lenyth, so that in a few hours it 

 is long-exserted, declined and the pilose, poUeu covered end turned up- 

 ward. No matter whether the flower is on an erect or inclined branch 

 the piloi^e end always turns upward, while the other portion of the style 

 assumes a horizontal or slightly declined position. One or two days after 

 the bud has opened the hairs on the style begin to wither and drop their 

 charge of pollen. At the same time stigmatic papillae are exposed and 

 ready for cross-pollination. Nectar is secreted by a fleshy disk surround- 

 ing the base of the style, and is protected from rain and the predatory 

 incursion of many insects by the triangular bases of the five stamens. 



Honey-bees and the beautiful metallic-green Agaostemon radlatus Say 

 are freiiuent visitors. They readily gain access to the honey by lighting 

 on the petals of the rotate corolla and inserting the tongue between the 

 style and bases of the stamens. Their visits, however, do not promote 

 fertilization, as their movements, in approaching the flower or in collect- 

 ing honey, never bring them into contact with the pollinated portion of 

 the style nor do thej- ever touch the stigma. 



C. Aiiivricaiia is cross-fertilized by a leaf-cutter bee, McgachWc brcvis 

 Say. It differs from the honey-bee in its structure and the way in which 

 it approaches the honey disk. It is armed with a dense brush of hairs 

 on tlie under side of the tail, instead of having pollen baskets on the 

 legs; it comes to the flower on the wing, in a direct, unhesitating way, 

 over the upturned stigma, which it frequently touches with the hairs of 

 its tail; it settles on the style with its head directed away from the 

 stigmatic end of that organ, and never comes in contact with the corolla 

 except with its fore feet. While in this position collecting honey the 



Note.— I am indebted to Mr. Ashmead, Bureau of Entomology, Department of 

 Agriculture, for identifying the bees named in this paper. 



