Yellow Flags

In recent years, many California herbaria have been actively digitizing their collections. This effort has resulted in the inclusion of over 2 million specimen records in the Consortium of California Herbaria (CCH), sixty-five percent of which are georeferenced (provided with geographic coordinates). This amazing accomplishment has made herbarium data available to a broad array of researchers including those studying climate change and developing conservation plans.

When seeking to understand a taxon's range, we now have the ability to computationally combine two lines of evidence, the description of the taxon's range provided in the Jepson eFlora and the distribution of georeferenced specimens in the CCH that bear that taxon's name (and known nomenclatural synonyms).

When mapped, most georeferenced specimens in the CCH fall within the taxon range described in the Jepson eFlora. However, about 6% of them show incongruence — the georeferenced location for a specimen falls outside of the distributional range of the taxon as it is described in the Jepson eFlora. These records are tagged (in both the CCH and Jepson eFlora) with a "yellow flag."

We invite all botanists to join the effort to help resolve these incongruences. We are especially interested in recruiting field botanists with first-hand knowledge of plant distributions and herbarium botanists with collections that can help resolve questions about a taxon's distribution. Resolving "yellow flags" will forward two goals: (1) making herbarium data as accurate as possible and (2) using georeferenced voucher specimens to improve the description of taxon ranges included in the Jepson eFlora.

There are several reasons that specimen coordinates might be at variance with the Jepson eFlora including: the need to revise range statements in the Jepson eFlora, incorrect coordinates assigned to specimens, misidentifications or unincorporated taxonomic revisions, and technical mapping issues.

For example, consider the taxon Xylococcus bicolor. In the original printing of The Jepson Manual, Second Edition, X. bicolor did not have the Peninsular Ranges Subregion (PR) indicated as part of its range, but yellow flag analysis revealed a large number of X. bicolor specimens collected from PR (left image). The yellow flagged records were resolved, in large part, by author confirmation to add PR to the distribution string of X. bicolor in the Jepson eFlora (right image). The addition of PR was based on the confirmation of specimens at UC/JEPS and RSA.

Left: Map of X. bicolor specimens in southwestern California, with yellow flags based on the original X. bicolor range statement.
Right: Updated map after the Peninsular Ranges Subregion (PR) was added to the X. bicolor range statement, resolving yellow flags.

If you would like to help investigate and resolve yellow flags, we welcome your input. In some cases, it is difficult to make inferences based on record data alone; specimens (at any herbarium) may need to be consulted. Please contact Staci Markos ( to get involved or send comments on particular taxa. Comments regarding individual specimens may also be submitted directly through the CCH portal.

Names with 100+ yellow flags

Here's an interesting one

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