When taxonomic authorities disagree: Rubus bifrons/armeniacus

[Ben Phalan]

Hi all,

I've been struggling recently to put the right name to the large, common weedy species of Rubus here in Oregon ("Himalayan blackberry"), but I'm confused with how this group is treated, perhaps because of inconsistencies between the multiple taxonomic authorities for plants. According to the Oregon Flora Project (not an iNaturalist authority) and also the guide "Shrubs to Know in Pacific Northwest Forests", R. bifrons and R. armeniacus are synonyms. However, both are active taxa on iNaturalist, both with many records in the Western US (several synonyms for R. armeniacus are given, including R. discolor).

The Plant List records both R. bifrons and R. armeniacus as valid names, but does not consider them synonyms (R. armeniacus is instead considered a synonym of R. hedycarpus armeniacus and R. macrostemon f. armeniacus).

CalFlora considers R. armeniacus a valid species, but does not appear to recognise R. bifrons.

GoBotany recognises R. bifrons, but not R. armeniacus, and applies the English name "Himalayan blackberry" to R. discolor (according to the Oregon Flora Project, R. discolor and R. procerus are "misapplied names" for R. bifrons).

The result for me (and I suspect others) is a lot of confusion. Are the concepts R. bifrons (Himalayan-berry) and R. armeniacus (Himalayan Blackberry) as currently used on iNaturalist different taxa, or synonymous? If synonymous, which authority should be followed when merging them? If different, can someone direct me to a guide to telling them apart?

I realise that there is a desire not to discuss taxonomy here, but any input on how to resolve the confusion from someone who knows about Rubus would be welcome!

[carex....@gmail.com]

As I understand the issue, the term "misapplied" is key to understanding the confusion.  Misapplied is a polite way of stating the species was misidentified.  The names R. armeniacus and R. discolor are accepted species.  Neither one is the species which has invaded the Pacific West Coast.  This misidentification has been a long time issue.  I just went to my copy of Peck, A Manual of the Higher Plants of Oregon, 1961 and verified that Himalaya Blackberry is identified as Rubus procerus!  I have seen a quote of an Oregon Pioneer horticulturist, Seth Lewelling, stating his excitement on seeing this wonderful blackberry.  

I suspect that what has happened is that the new invasive Rubus was identified on the basis of incomplete understanding of the taxons involved.  This may have stood for nearly 100 years until the proper identification was finally established, maybe?  

The general practice is to accept the local regional authority for the correct name.  These herbera are generally more responsive to the current literature then the world wide authorities. Why CalFlora does not recognize R. bifrons, I do not know and would refer the question to the Jepson Herbarium.  

[Ben Phalan]

Thanks! So does this mean that the >1000 observations of "R. armeniacus" from the west coast may be misidentified? I will get in touch with the herbarium as you suggest.

[Todd Ramsden]

I found some history of the Jepson Manual treatment here:

http://ucjeps.berkeley.edu/cgi-bin/get_cpn.pl?87465&expand=1

If I follow correctly, it sounds like the author of the JM2 and co-author of the Flora of North America treatment (Dr Lawrence Alice) now lumps some of the weedy species as Rubus bifrons (including R. armeniacus, R. discolor, R. procerus, but not R. ulmifolius)

http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242417158

[Ben Phalan]

Thanks Todd. My reading of the efloras text was that various authors "distinguished between Rubus bifrons and another species (referred to as either R. discolor or R. procerus P. J. Müller ex Boulay, both often considered synonyms of R. armeniacus)" but that the two are very difficult to tell apart. So there may genuinely be two species in this complex present, but I rather doubt whether many of the IDs based on photos on the site are accurately separating them.

[Charlie Hohn]

if so, it's clearly another case where we need multi=species complexes

[Aaron Liston]

There is  a newer taxonomic study that convinced me we have 2 species in Western Oregon, Rubus armeniacus and R. praecox. Bruckart et al consider R. bifrons a European species not introduced to the US. Importantly, they found a difference in susceptibility to Phragmidium violaceum, a rust fungus used in Australia for biological control of Rubus, and apparently a rogue introduction to Oregon ca. 2004. See

http://www.bioone.org/doi/abs/10.1017/inp.2017.12  (available via Sci-Hub).

[Ben Phalan]

Thank you for this, Aaron. So, based on this paper, there are two similar species in W Oregon:

Rubus armeniacus - with larger, pink or whitish-pink flowers, long stamens, and straight prickles on the inflorescence axis (flower stalk).

Rubus praecox - with slightly smaller, white flowers (buds can be pink), shorter stamens and curved prickles on the inflorescence axis. Of the two, only this species is susceptible to the Phragmidium rust fungus that causes small brown spots on the leaves. Presence of the rust seems like a useful supporting identification feature.

It's a shame that flowering is over for the year - too late now to go out and look for these flower differences!

[carex....@gmail.com]

The Bruckart et al paper is interesting in that it identifies two two similar species of Rubus with different responses to an infectus rust.  However, it does not address the taxonomy of Himalayan Blackberry.  R. Gaire et al http://www.nrcresearchpress.com/doi/full/10.4141/cjps-2014-402#.WfZROPkrLiw provided an interesting overview of the taxonomic question.  This is the crux of the question at hand.  Reading across the recent papers, I note a number of questions that raise a question of species concept.  The work cited by Bruckart (Clark et al.) may be a step in that direction. 

The current name R. bifrons is the name accepted and advanced by the OSU Herbarium.  That name may-very-not stand the test of time.  The accepted name may well prove to be something different.   I rely on the established taxonomic expertise to determine the accepted name.

[Ben Phalan]

Many thanks for this reference, @carexobnupta. It seems the taxonomists still have some work to do! I did not get a response from the Jepson herbarium. Also, I notice that all of these species are considered microspecies within the complex <i>Rubus fruticosus</i> agg., but are not treated that way in the iNaturalist taxonomy - can the taxonomy accommodate species complexes like this one?

Ben

[carex....@gmail.com]

I have started looking at Phragmidium violanceum and ran across a 2008 paper from Australia http://aem.asm.org/content/74/17/5504.full.  This article stated that there are some 15 taxa of Rubus fruticosus L. aggregate that occur in Australia.  Following up on that, I ran a iNaturalist search on the Australian Rubus.  It appears that the standard name for Himalayan Blackberry there is Rubus fruticosus L. aggregate as in New Zealand.  It is interesting to see different blackberry features with the occurance of rust.  

It is surprising to see the use of the Rubus fruticosus taxon in North America.  There are some 400 observations.