Species: Artemisia campestris var. wormskioldii

Restricted to the Columbia Basin Province in Washington and, formerly, Oregon. Only two natural occurrences of this variety remain in Washington, separated by 325 river km and three large hydroelectric dam/reservoir complexes (Priest Rapids Dam, McNary Dam, and John Day Dam). At least three, possibly as many as eight, extirpated Oregon sites have been documented, in Sherman (element occurrence), Multnomah (element occurrence), Hood River (WA NHP 1997), Wasco (WA NHP 1997), and Umatilla (Oregon State University Herbarium 2007) counties. These sites are periodically re-surveyed, but plants have not been found. It is likely that disturbances due to the construction of several dams and subsequent flooding of habitat resulted in the extirpation of these occurrences (Carlson 1997 and Rush 1999 cited in McCracken 2007). The Oregon Department of Agriculture (ODA) Native Plant Conservation Program initiated reintroduction efforts into the former Oregon range in spring 2008, planting material propagated from the Grant County, WA occurrence at one site in Wasco County, OR. ODA believes that the following criteria must be met before these plantings can be considered part of the extent of occurrence: a minimum of five years of stable (and sufficiently high) plant numbers, evidence of reproduction and recruitment, and sufficient confidence that site management is appropriate (K. Amsberry pers. comm. 2008). Range extent is difficult to estimate with only two known sites. Arbitrarily assuming that plants might grow up to 150 m from the river's edge on either bank yields an estimate of just less than 100 square km (110 square km if the reintroduction site is included); arbitrarily setting the range extent equal to the area of the river itself between the known sites (since plants also occur on river islands) yields an estimate of 4500 square km (4800 square km if the reintroduction site is included). Reports of this variety from Canada, California, and Greenland (Kartesz, pre-1997 datasets) are erroneous; in his published 1999 floristic synthesis, Kartesz accepts only the Oregon and Washington reports for this plant.