I received a reprint request this morning for Wolfe and Randle (2001), which prompted me to review the article. This was a small survey of four species of Hyobanche using inter-simple sequence repeat markers (ISSRs). One of the results was “Ordination of ISSR data revealed discrete groups, although H. glabrata and H. rubra were indistinguishable.” Well, ahem, it turns out that we really only had accessions of H. glabrata in that survey. I didn’t actually have any collections of H. rubra until 2003, after an intense search in the summer rainfall areas of South Africa and Lesotho.
We’ve been doing some extensive work with an AFLP survey of the entire genus, and I’ve been working on the taxonomic revision of the genus by doing a morphometrics study. It turns out that H. glabrata and H. rubra are, indeed, separate entities – both morphologically and molecularly.
The taxonomy of the genus has been very confused for more than 100 years, but I am finally teasing apart the morphological differences among species, and preparing new species descriptions. To say that this is a confusing genus is a huge understatement, primarily because there are few characters that are easily distinguishable to identify species. For H. glabrata and H. rubra, the primary differences are in color and amount of pubescence on the corolla. Hyobanche rubra tends to be pink to salmon in color, with very hairy corollas, whereas H. glabrata is bright red to orange or yellow in color and is, at most, sparsely hairy near the corolla mouth. Hyobanche rubra is found in the summer rainfall region of the eastern part of South Africa and along the south coast where rainfall is year-round. Hyobanche glabrata, in contrast, is found mostly in the winter rainfall regions of South Africa.
Here are some of my field photos to help in recognizing the two species:
All photos by Andi Wolfe ©2002 to 2013
Wolfe AD, Randle CP (2001) Relationships within and among species of the holoparasitic genus Hyobanche (Orobanchaceae) inferred from ISSR banding patterns and nucleotide sequences. Systematic Botany 26, 120-130.