Document Type


Date of Degree Completion

Spring 2011

Degree Name

Master of Science (MS)



Committee Chair

Tom Cottrell

Second Committee Member

Kristina Ernest

Third Committee Member

Linda Raubeson


Erigeron basalticus (basalt daisy) is a rare plant occupying a very restricted range of approximately 52 km2 in only two counties (Kittitas and Yakima) in central Washington State. Growing out of the cracks and crevices of basalt columns, the population of E. basalticus is fragmented and confined to its unique niche. The entire population consists of approximately 8,000 individuals.

This study focused on the pollination system of E. basalticus, specifically self-pollination and a determination of the most frequent insect visitors. Erigeron basalticus was determined to be primarily self-incompatible, therefore, pollinators will be important for successful pollination to occur.

A total of 143 observational hours were logged in 2005 and 2006 in an effort to determine potential pollinators of E. basalticus. Only insects and no other potential pollinators were observed visiting E. basalticus flowers. At least 13 different genera of insects observed, mostly consisting of Diptera (flies) and Hymenoptera (bees and wasps). The most frequently seen visitors and probable pollinators were Geron sp., Colletes spp., Augochlora sp., and Mythicomyia sp.; however, Mythicomyia may not be a pollinator due to its small size and lack of body hair.

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Botany Commons