Origin:
selected vouchers: Not at WTU; WS?
Notes: WA report based on checklist by Naas et al. 1990, but not reported in H&C for WA.
Draft treatment in Flora of North America lists WA within the range of this taxon, but no specimens at WTU. Uncertain as to presence of specimens at WS.
Henderson and Piper both labeled collections they made from the Olympic Mountains as H. boreale, however examination of the specimens by D. Giblin in 2009 showed that they are H. occidentale.
References: (none)