Cascade Knotweed (Polygonum cascadense W.H. Baker)

↑Range - Expand

Legend	Color
Native
Not Present
Native or Introduced or Not Present
Native or Expanded or Not Present

This map is based on our research. We have checked its accuracy to Level 3 ecoregions. Although this plant occurs somewhere in each of these regions, it may only occur in a small part of some or all of them.

BONAP and USDA PLANTS both report this species as also native to Grant County, Oregon, but the Consortium of PNW Herbaria shows no records there. We found a single 2009 record from the Field Museum of Natural History (Botany) Seed Plant Collection in Chicago. If assuming this record is a correct ID, it is not clear whether that record is a native population, an introduction, or a waif that failed to establish. We have not seen evidence of a sustaining population anywhere east of the Cascades; given that this species is abundant in parts of the Cascades and does not venture at all into the drier eastern slopes, it seems unlikely it would survive in the drier Blue Mountains, but it could perhaps have an isolated relict population in the highest-elevation parts of these mountains. Similarly we found one isolated record in the North Cascades, far from the rest of the range, but have not seen evidence of a sustained population there.