Ask Mr. Smarty Plants

The taxonomy of the genus Viola has been in flux for some time.
 
The entire paragraph on the Viola affinis (Sand violet) page in NPIN (Native Plant Information Network) about it being subsumed by V. missouriensis was an error.  It has been removed.  When we did the research on that page, we clearly entered information dealing with another taxon.  The lists of synonyms and range were also erroneous and have now been corrected.
 
The NPIN record for Viola missouriensis (Missouri violet) was for the most part correct, but some of the states in its known range were not listed.  Those errors have also been corrected.
 
The taxonomic authority for USDA Plants Database (and the Lady Bird Johnson Wildflower Center) is The Synthesis of North American Flora, the database of the Biota of North America Project (BONAP).  It is my understanding that ARS-GRIN (Agricultural Research Service-Germplasm Resources Information Network) and ITIS (Integrated Taxonomic Information System) use a variety of taxonomic references.
 
Now to what’s what.  Both USDA Plants Database and The Flora of North America recognize Viola missouriensis as an accepted name.  ITIS lists it as a synonym of Viola affinis (the accepted name according to ITIS).  ARS-GRIN has it as a synonym of V. sororia var. missouriensis.
 
On the other hand, ARS-GRIN lists Viola affinis as a synonym of V. sororia var. affinis.  As previously mentioned, ITIS considers A. affinis an accepted name.  USDA Plants also has it as a good name but The Flora of North America project does not yet address that taxon (It’s a work in progress).
 
Who to believe?  The simple answer is, believe us.  However, the correct name for any species is the most recent validly published name for that taxon.  The question of validity sometimes takes a few years to sort out.  Our authority, The Synthesis of North American Flora, takes a conservative approach to name changes to allow the scientific community time to evaluate and comment on new combinations and revisions to the scientific record.  We think that’s a wise approach.

Thank you for pointing out the inconsistencies for these species in our Native Plant Database so that we could correct them.  Our goal is for the information we provide to be as accurate as possible.