Premise: Allium campanulatum is a species of wild onion known by the common name dusky onion or Sierra onion. This is a flowering plant native to the western United States from southeastern Washington and northern Oregon to southern California, and western Nevada. The dusky onion grows in foothills and mountains, especially in dry areas, such as chaparral habitats.
Hypothesis: Allium campanulatum is found more frequently in southeastern Washington than in northern Oregon.