Some comments on the taxonomy of Delphinium (Ranunculaceae) in western Oregon
In preparing the treatment of Delphinium for a future volume of Flora of Oregon, some taxonomic decisions were made that conflict with the 1997 treatment of the genus by Warnock in Flora of North America. The choice of groups to be recognized is based on the present author’s opinion that rapid evolution of Delphinium taxa occurred in the Willamette Valley following habitat disturbance caused by catastrophic flooding from the late-glacial-age Spokane Floods. Delphinium pavonaceum Ewan, D. leucophaeum Greene, and D. oreganum Howell, which are endemic to the Willamette Valley, may have evolved in the ca. 12,000 years since the floods occurred. These 3 groups are here given species rank, unlike their treatment in Flora of North America. This is in line with how the taxa are viewed by Oregon botanists concerned with the rare and endangered species of the state. Lectotypification is necessary for D. pavonaceum. A further taxonomic change is the reduction of D. basalticum M.J. Warnock to synonymy under D. glareosum Greene.
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