Ask Mr. Smarty Plants

First of all, there is no official authority for common names of plants. They can, and do, vary from region to region, culture to culture and language to language.  However, the Latin or botanical name is meant to be the same and recognized everywhere—in any region and by any culture or language. Nevertheless, plant taxonimists, in their infinite wisdom, do often change the botanical names of plants.  Renaming them isn't done, no matter what we might think, simply to irritate us who have learned the former Latin name! There are a number of reasons for name changes, but most have to do with new evidence coming to light which necessitates name changes in order to be in compliance with The Code.  The Code is the International Code of Botanical Nomenclature (Vienna Code) adopted by the Seventeenth International Botanical Congress, Vienna, Austria, July 2005 and published in 2006.  The Code is available online and is the official document containing the rules governing the naming or renaming of plants.   

For valid botanical names in the United States one consults the ITIS (Integrated Taxonomic Information System) database. 

ITIS shows five unaccepted synonyms for the accepted Alophia drummondii (propeller flower).  These synonyms are:  Cypella drummondii, Eustylis purpurea, Herbertia drummondii, Nemastylis purpurea, and Tigridia purpurea.  In our Native Plant Database we show three common names—propeller plant, purple pleat-leaf and pinewoods lily.

Herbertia lahue is the accepted name listed by ITIS for Herbertia lahue (prairienymph).  There are no synonyms listed for this species.  In our Native Plant Database we show two common names—prairienymph and herbertia.  But then there is Herbertia lahue ssp. caerulea (prairienymph) with five unaccepted synonyms listed: Alophia drummondii, Herbertia caerulea, Trifurcia caerulea, Trifurcia lahue ssp. caerulea.

We can see how you could be confused!  You can read the accounts from Flora of North America for Alophia drummondii,  and Herbertia lahue which give us some insights into the confusion about the two names and gives us detailed descriptions of the two species. The explanation under the entry, Herbertia, says that the two names have been confused because of "an erroneous interpretation of the identity of the type species of Alophia (P. Goldblatt 1975)."