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Results tagged “june-04”

Jun 4, 2012: Hemieva ranunculifolia

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.

Jun 4, 2007: Ephedra frustillata

I've covered most broadly-defined groups of plants on Botany Photo of the Day in the past two-plus years. However, here's a representative of one group that I've neglected to date, the gnetophytes.

Traditionally, seed-bearing plants were thought to be divided into two groups: the angiosperms (flowering plants with seeds developing within a carpel) and gymnosperms (non-flowering plants with seeds developing naked on the scale of a cone or equivalent). While the angiosperms remain a phylogenetically-sound group (i.e., all derived from a common ancestor), the gymnosperms are now thought to be an artifical grouping. In other words, we use the term gymnosperms for non-flowering seed-bearing plants because it is convenient to do so and not because it reflects a common-ancestor evolutionary relationship among the plant groups with those qualities.

The gnetophytes, including the genus Ephedra, are one of four groups traditionally thought of as gymnosperms (the other three being conifers, cycads and ginkgos). However, they differ from the other three groups in that they contain vessel elements, a cell type found in the water-conducting tissues. Interestingly, vessel elements are commonplace in the flowering plants. The presence of vessel elements in the gnetophytes has long been held up as one of the hints that the gymnosperms are an artifical grouping, with the corollary that the evolutionary relationships among the groups is more complex than it seems at first glance.

Ephedra is typically distributed across the northern hemisphere, but Ephedra frustillata is one of the exceptions. It is found in Tierra del Fuego as well as mainland Argentina and Chile (here's a photo of it in habitat). The macro photograph shows the pollen-producing male cones in detail (and they were producing heavily; the legs of my tripod were painted yellow after taking these images).


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