About the Washington Flora Checklist

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How to Cite:

The Washington Flora Checklist is an ongoing project with frequent updates. When citing the checklist, please include the date on which the checklist was cited or accessed.

To cite the entire checklist using today's date:

Weinmann, F., P.F. Zika, D.E. Giblin, B. Legler. 2002+. Checklist of the Vascular Plants of Washington State. University of Washington Herbarium. https://burkeherbarium.org/waflora/checklist.php. Accessed 19 Jun 2024.

Contact Us:

General inquiries about the WA Flora Checklist can be addressed to David Giblin. Technical questions and the web site issues may be addressed to David Giblin or Ben Legler.

Email addresses:
[1] = @uw.edu
[2] = @uidaho.edu

Dr. David E. Giblin
Herbarium Collections Manager
Box 355325
University of Washington
Seattle, WA 98195-5325

Ben Legler
Herbarium Collections Manager
Stillinger Herbarium
University of Idaho
875 Perimeter Dr. MS 1133
Moscow, ID 83844-1133

Dr. Richard G. Olmstead
Herbarium Curator
Burke Museum Curator of Botany
Professor of Botany, Biology Department
University of Washington
Seattle, WA 98195-5325
1-206-543-8850; 1-206-543-6594


In the fall of 1998 Fred Weinmann initiated a series of meetings to discuss the development of a checklist for the flora of Washington State and the possible publication of a new flora for the state. From these meetings a set of protocols was developed, with a preliminary draft checklist assembled by 2001-2002 with the help of Peter Zika and about a dozen other volunteers. Paul Rodman volunteered his time and expertise to assemble the programs, databases, and website to facilitate development of the checklist and make it available online. Over 1,000 hours of time had gone into development of the checklist to this point, with Fred Weinmann and Peter Zika having compiled the bulk of the checklist contents. During this period the checklist was called the Washington Flora Project and was available online at http://flora.ilangainc.com/.

Additional revisions were made to the checklist during 2002-2003, after which development on the checklist came to a halt due to difficulties in updating the checklist database. A few additional revisions compiled during 2003-2004 never made it into the checklist.

In 2006 discussions between the University of Washington Herbarium, Fred Weimann, and Peter Zika led to a proposal to migrate the checklist to the Herbarium for maintenence and further development. Under this proposal the checklist was to be redesigned to allow continued revisions to the checklist data, thereby preventing the stagnation and loss of the checklist. A grant from the Bureau of Land Management provided funding for this transfer. The Herbarium provided the remaining funding, server space, and staff support needed to transfer and maintain the checklist.

In early 2007 the new checklist databases and website were completed and made available online in a new format that allows continued revisions and development of the checklist data, turning the checklist into a dynamic document that can be easily updated as new information becomes available. At this time the name of the checklist was changed to the Washington Flora Checklist and the checklist web address was moved to https://burkeherbarium.org/waflora/checklist.php.

In late 2018 the 2nd Edition of the Flora of the Pacific Northwest was published. Following completion of this revised Flora, the Washington Flora Checklist underwent a major update to align classifications, nomenclature, and synonymy with that used in the revised Flora. The Checklist was also merged with a broader checklist providing coverage for the greater Pacific Northwest region and elsewhere, with the WA Flora Checklist displaying a subset of the names in this larger list. The unified checklist ensures nomenclatural consistency across the Herbarium's online resources, including the Consortium of Pacific Northwest Herbaria web site and the Burke Herbarium Image Collection web site.

Past Floristic Work in Washington State

The Flora of the State of Washington was authored by Charles V. Piper and published by the U.S. National Herbarium in 1906. This represents the only flora which is both comprehensive (for the time) and limited to the vascular plants of Washington State. More recently, the flora/manual most widely used by field botanists and other botany practitioners in the state was the Flora of the Pacific Northwest (Hitchcock and Cronquist 1973) and its 5 part precursor, Vascular Plants of the Pacific Northwest, Parts 1-5 (Hitchcock et al. 1955-1969). These latter publications were comprehensive for their time and were particularly advantageous to botanists of Washington in that the entire state is included within the geographic range covered.

Justifications for a state checklist

There have been several sources of revisions to the Washington state flora in the decades since publication of the Hitchcock et al. treatises. Much research has been completed which has resulted in taxonomic and nomenclatural revisions, native species have been discovered which were not previously known to occur in the state (including a few undescribed or newly described species), and many taxa have become naturalized in the state via accidental introduction or by escape from cultivation. Some of these changes have been published in various places, including the Flora of North America; however, the nomenclature and taxonomy is often inconsistent and coverage incomplete. Other changes (e.g. additions to the state flora) are recorded by individuals or agencies but have not been published and therefore are not known beyond a few individuals. All of these events combine to create a need for a current, frequently updated checklist for the native and naturalized vascular plants of Washington state.