486 IOWA ACADEMY OF SCIENCE 



pollination, so I stretched cheese cloth and mosquito netting 

 over wire domes, which by means of stakes driven into the 

 ground I attached securely over plants just prior to their 

 blooming season. 



My stay was too brief to permit me to obtain definite results 

 in all cases, but I can report as follows : 



1 — No seeds on covered plants, seeds on uncovered: Polemon- 

 ium confertum, Trifolium dasyphyllum, Silene acaulis. 



2 — Practically as many seeds on covered as on uncovered 

 plants: Ranunculus inamoenus, Oreoxis alpina, Sieversia tur- 

 birVataj Erysimum ivheeleri. 



It is worthy of notice that the flowers that require insect 

 visits for pollination are mainly the bee flowers, while those 

 that get along without them are principally the fly flowers. 

 Perhaps the real reason for this difference is the relative ar- 

 rangement of the floral parts. The bee-flowers are long-tubed 

 and are apt to have stamens and pistils relatively remote from 

 one another. On the whole the flowers of the two groups are 

 about equal in showiness. 



Of course when the wind is quite strong or when rain or 

 snow is falling or the clouds are dense there is a scarcity of 

 insects in sight. But selecting comparable weather and exclud- 

 ing the honey bee, which does not live at high altitudes, it seems 

 to me that the flowers above timberline are as much visited by 

 insects as are those of lower altitudes, and I have no reason to 

 suppose that they are any less dependent for pollination upon 

 their insect visitors. 



Dr. L. H. Pammel, who has given some attention to Alpine 

 flowers in various sections of the Rocky Mountain region, thinks 

 that insects are practically as abundant on Alpine as on low- 

 land flowers. 



I must express my appreciation to Dr. Francis Ramaley for 

 extending to me the courtesies of the Colorado University La- 

 boratory at Tolland. 



LITERATURE CITED. 

 Nageli, C. Von, Entstehung und Begriff der naturhistorischen Art, 



Miinchen, 1865. 

 Bonnier, Gaston, Les Nectaires. Annates Des Sciences Naturelles (Bot- 



anique), Paris, VIII, 1879. 

 Miiller, Hermann, Die Alpenblumen, ihre Befruchtung durch Insecten 



und ihre Anpassungen an dieselben, Leipzig, 1S81. 

 Schrbter, C, Das Pflanzenleben der Alpen, Zurich, 1904. 





