D-3 



an obligate or near-obligate outcrosser; however, I feel that an expanded 

 study specifically examining seed set of bagged plants is necessary to 

 confirm these results. 



The results of this study suggest that Spalding's catchfly is an 

 obligate or near-obligate outcrossing species capable of being pollinated 

 by bumblebees. Although bumblebees are common and ubiquitous, overgrazing 

 by livestock can have a detrimental effect on bee populations and 

 consequently on the reproductive effort of the plants they pollinate 

 (Sugden 1985) . In the absence of severe overgrazing and pesticide use, 

 seed production by Spalding's catchfly will probably not be curtailed by 

 pollinator limitation. 



UTERMiiRE crrnD 



Faegri, K. and L. van der Pijl. 1971. The principle of pollination 

 ecology. Pergamon Press, Oxford. 



Heidel, B. 1980. Report on the conservation status of Silene 



spaldinqii . Report prepared for the U.S. Fish and Wildlife Service, 

 Office of Endangered Species, Portland, OR. 



Sugden, E. A. 1985. Pollinators of Astragalus monoensis Bameby 



(Fabaceae) : new host records; potential inpact of sheep grazing. Great 

 Basin Naturalist 45: 299-312. 



Prepared by: Peter Lesica 



TVie Nature Conservancy 

 Montana/Wyoming Office 

 Box 258 



Helena, m! 59812 

 September, 1988 



