A question I am frequently asked at presentations, particularly after presenting the “new name” of a species, is: “Why do plant names change?”. The answer invariably is, “Well, it depends…”, followed by an elaboration with some examples. I can apparently add today’s species to my repertoire of examples, as it is a relatively straightforward one to explain.
If you are familiar with this species, you will likely know it as Suksdorfia ranunculifolia, or buttercup-leaved suksdorfia. That’s been the name attached to it for about a century, though this has been recognized as a distinct species for almost two centuries. It was first published as Saxifraga ranunculifolia by William Hooker in 1832. Only four years later, the prominent (but controversial) botanist Constantine Rafinesque published his assertions that not only was it not a saxifrage, but it was also from a previously-undescribed genus. In 1836, he proposed the name Hemieva for the genus, and renamed it Hemieva ranunculifolia (and, more technically, Hemieva ranunculifolia (Hook.) Raf.). This name languished for a long time, disregarded for the most part–this was toward the end of Rafinesque’s life, when he was generally ignored.
In 1879, Asa Gray described a new taxon in the saxifrage family, Suksdorfia violacea, for which he had to erect the genus Suksdorfia. Twelve years later, Adolf Engler proposed transferring Saxifraga ranunculifolia Hook. (aka the ignored Hemieva ranunculifolia (Hook.) Raf.)) into Suksdorfia, and this became the generally-agreed upon standard for beyond the next century: Suksdorfia ranunculifolia (Hook.) Engl.. With the transfer of Saxifraga ranunculifolia into Suksdorfia, strictly speaking, both should have been renamed Hemieva, but Rafinesque’s name was rejected.
With the advent of molecular techniques in the late 20th-century, some of the new data gathered suggested that Suksdorfia ranunculifolia possibly had an ancient hybridization with a species of Boykinia, such that determining relationships based on chloroplast DNA put this one of the two Suksdorfia species as a closer relative to the group of Boykinia species than to its sister taxon, Suksdorfia violacea. However, an assessment of the ITS region showed that the two Suksdorfia species grouped together and were closely related to Bolandra, in accordance with the existing morphological evidence (see: Soltis et. al. 1996. Discordance between ITS and chloroplast topologies in the Boykinia group (Saxifragaceae). Systematic Botany. 21(2):169-185.). The authors concluded that some taxonomic revision may be required.
As part of the development of the 2nd edition of The Jepson Manual, the editorial committee reviewed the 1996 paper as well as subsequent evidence, and made the determination that Suksdorfia ranunculifolia should be recognized as being in a genus distinct from others in the Saxifragaceae. Due to the principles of priority (Rafinesque was the first to place this taxon into a distinct genus), Hemieva ranunculifolia, first proposed in 1836, became the “new” name for Suksdorfia ranunculifolia.
Hemieva ranunculifolia is native to western North America, reaching its northern extent in British Columbia and Alberta and its southern extent in California, where it is ranked as “fairly endangered” in the state. The plant in today’s photograph was growing on a wet rock wall that had been blasted for a railroad right-of-way. Only a few plants in the shadiest spots remained in bloom as of two weekends ago.