Leslie, in most cases we base our data on the latest information in the Catalogue of Life, particularly when this information comes from World of Plants or some other highly reliable source.
In the case of Salvia, however, the COL information on Salvia species comes mostly from ITIS, which is a respected source, but is highly limited and does not list all of the accepted species names. Accordingly, we used the data from The Plant List for our Salvia entries, except in those cases in which TPL data were nullified by information from ITIS and GRIN. In general, we avoid The Plant List, because it is a rather undiscriminating source and consequently contains much information (or, more properly, misinformation) that's obsolete or downright inaccurate.
The TPL listings for S. africana-lutea and S. africana-caerulea are contradicted by GRIN, which lists them as synonyms of S. aurea and S. africana. Furthermore, according to GRIN, they aren't even true synonyms. They're invalid names and are listed as synonyms only for the convenience of people looking for them. Here's the GRIN listing for Salvia africana-lutea, for instance. Please note that the GRIN information was updated in January 2014, whereas the last update of the information in The Plant List is dated March 2012 (and probably was always misinformation to boot).
http://www.ars-grin.gov/cgi-bi...
