Rudbeckia 'Herbstonne' - What IS it really?

Google Rudbeckia 'Herbstonne'.  I promise you will find endless repeated statements about it being a cultivar of R. laciniata, R. nitida OR a hybrid of the two.  Never any written statement to justify why it's listed as one or the other or a mix of the two!  As I really like this plant I of course had to know what its real identity is.  I began to dig through the plants.usda.gov database where I saw pictures of R. nitida and realized R. 'Herbstonne' really looks nothing like it (to a plant geek at least).  Then I realized that R. laciniata actually further breaks down into multiple varieties with a good bit of morphological variation, but this particular database didn't have enough info to learn how to differentiate them.  Next, Google took me to eFloras.org which is home of plant identification keys for just about any plant you could think of.  The level of detail in the keys borders on overwhelming even to a plant geek.  I had to go back to Google for help understanding numerous words, but eventually I was able to trudge my way through the identification key for the genus Rudbeckia.  

The following is my story (Rated: Extreme Geek)...

Using the very detailed eFloras.org database I followed the identification key for Rudbeckias and found that the species R. laciniata has a very wide geographic distribution with a significant amount of observable variation within the species to the extent that multiple "variety" subcategories are recognized. All of the observable characteristics which I have been able to take note of in R. 'Herbstonne' place it well within the recognized variations of R. laciniata varieties. Additionally, its characteristics do not at all line up with the defining features of R. nitida. Within the R. laciniata varieties I found 'Herbstonne' most closely matched the characteristics of variety humilis (aka digitata). Additionally, R. 'Herbstonne' does not appear to spread by seed which indicates it may have a mismatched chromosome ploidy. While crossing R. laciniata with R. nitida would in fact create such a mismatched ploidy, there is also at least one known variety of R. laciniata which differs in ploidy from the other varieties and therefore if these subcategories of R. laciniata were to cross with each other the mismatched ploidy and resulting lack of seed production would also be possible. Given that R. 'Herbstonne's observable characteristics fall within the normal variation of the broader R. laciniata species, I believe the later scenario is most probable, but would require genetic analysis to confirm. I don't know anyone working on that... :)

So...  How did this name mix up start in the first place? 

As you may have guessed by the name "Herbstsonne", this variety was originally selected in Germany.  When I have looked this variety up on German language websites, I have only found it listed as being a selection of Rudbeckia nitida.  They never claim it to by a hybrid between R. nitida and R. laciniata.  Being as R. nitida is a very different plant with un-lobed elliptic to lanceolate shaped leaves (Ref. eFloras.org), the most obvious explanation is that the original breeder of this plant could have received R. laciniata seeds mislabeled as R. nitida and being on the other side of the world without access to the wealth of information we have today, they simply trusted that the resulting seedlings were of R. nitida and had no information to cause doubt as to that.  

Despite German references not claiming any hybrid status, many English language references do make this claim.  Again, despite 'Herbstsonne' clearly fitting within the R. laciniata species, American nursery growers have often lacked the confidence to drop the "nitida" from its name, so recognizing this plant has clear "laciniata" traits they assumed that it must actually be of hybrid origin.  

Going back to the fact that the many references in the original language fail to claim any sort of hybrid status, we can be very sure that the lack of R. nitida features and lack of hybrid claims put Rudbeckia 'Herbstsonne' safely within the species Rudbeckia laciniata.

Share on Facebook         Share on Twitter

Click here to see my full plant description and to check out all the cool plants currently available from my nursery Johann's Garden - Nursery & Farm

Pick up only, located Pierce county, WA