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Botanical Identity Crisis

October 28, 2012

or Why Do Genus Names Keep Changing?

A row of bleeding hearts blooming in the garden (photo credit: Jean Potuchek)When I posted about spring clean-up in my garden last March (Time for Spring Clean-Up), I referred to the old-fashioned bleeding hearts in my garden, the species formerly classified as Dicentra spectabilis, by their new botanical name, Lamprocapnos spectabilis. This brought cries of outrage or dismay from several readers. One commented plaintively, “Don’t tell me that they have changed the genus name of bleeding-hearts. I don’t think I can take it anymore,” and another resisted the change, noting “Afraid that Lamprocapnos spectabilis will never trip off my tongue or keyboard Jean ~ I will just stick to Bleeding Hearts from now on….”

Like others, I found myself particularly disturbed and saddened by this name change. Perhaps it’s because Dicentra spectabilis was such a pretty name for a pretty spring flower, or because this particular name was one of the first botanical Latin names that I learned. But as someone for whom scientific thinking is an important part of both my work and my identity, I also felt uncomfortable resisting new scientific knowledge. So I decided I needed to learn more about  botanical taxonomy and why it has seemed so changeable of late.

To understand this phenomenon, I talked with botanist friends and colleagues, read explanations written for a lay audience (e.g., this one put out by the Kew Royal Botanic Gardens), delved into botany textbooks, and struggled through scientific articles. Here is what I learned:

From one of my most important sources of information, the influential botany textbook, Raven’s Biology of Plants, 8th edition (published by W.H. Freeman), I learned the distinction between taxonomy and systematics. Taxonomy is the science of classifying organisms. The basic principle of taxonomy is that organisms are arranged in a hierarchical system of categories. Thus, the kingdom of plants is divided into phyla, each phylum is divided into classes, each class is divided into orders, each order is divided into families, each family is divided into genera, and each genus is made up of a number of species. The basic principle of classification is that, at any level of the classification system, plants within the same group should be more like one another than they are like plants outside that group.

But alike how? There are many different types of characteristics that can be used to classify plants. Early systems of classification were based on the appearance or habit of the plants. Linnaeus, for example, organized flowering plants into 24 classes based on the number and arrangement of stamens in each flower. Although Linnaeus’s binomial plant naming system stuck, his particular criterion for classifying plants didn’t. As botanical science developed, such arbitrary systems were replaced by “natural classifications” based on systematics – the scientific study of the diversity of plants and the relationships among them (particularly relationships based on evolution).

The dominant system being used to classify plants today is cladistics. This version of systematics is  based on the concept of a “clade” or all the evolutionary descendants of a single common ancestor. Under the principles of cladistics, “… a genus should consist of all species descended from the most recent common ancestor – and only of species descended from that ancestor. Similarly, a family should consist of all genera descended from a more distant common ancestor – and only genera descended from that ancestor.” (Raven’s Biology of Plants, 8th edition, p. 238)

In earlier taxonomies based on cladistics, the evolutionary relationships among plants were hypothesized based on observable characteristics. All this changed with the development of “molecular systematics.” Just as genetic sciences have enabled biologists to map the human genome and the genomes of many animals, so too have the genomes of plants been mapped, enabling botanists to see which plants are most closely related to one another. This can sometimes lead to big surprises. For example, without the evidence of plant DNA, no one would have guessed that the water lotus (Nelumbo) is more closely related to sycamore and plane trees (Platanus) than to water lilies! (Raven’s Biology of Plants, 8th edition, pp. 242-3)

A profusion of Lamprocapnos spectabilis blooms in my Gettysburg garden in spring (photo credit: Jean Potuchek)In 1997, a group of botanists (Magnus Liden, Tatsundo Fukuhara, Johan Rylander, and Bengt Oxelman) published an article in the scientific journal Plant Systematics and Evolution entitled “Phylogeny and classification of Fumariaceae, with emphasis on Dicentra s. l, based on the plastid gene rps 16 intron.”  This formidably named article was an application of the new molecular systematics to the Fumitory plant family (Fumariaceae), which includes the genera  Dicentra and Corydalis (among others), and used a particularly important gene to examine the evolutionary relationships among these plants. What the authors found was that Dicentra spectabilis did not share a common immediate ancestor with the other Dicentra species and therefore, under the principles of cladistics, did not belong in the same genus.

There have been some reports in the garden blogosphere that the entire Dicentra genus was disbanded. That doesn’t seem to be the case. The very similar looking North American native plants Dicentra eximia and Dicentra formosa still seem to be classified as Dicentra; it’s just that the plant formerly classified as Dicentra spectabilis turned out not to be as closely related to these as had been assumed from their appearance. As Liden et al. explain, “A splitting of Dicentra, with the consequence that the name of the commonly grown D. spectabilis will have to change, is unavoidable if we aim at a reflection of evolutionary relationships in our formal classification.” (p. 414)

But granted that taxonomic integrity required renaming this favorite plant, why did they have to give it such an ugly name? Why replace the soft sibilant sound of Dicentra with the hard, explosive p sounds of Lamprocapnos. It turns out that scientists who propose taxonomic changes cannot just use any names that they want; plants names are governed by a set of rules set out in the International Code of Botanical Nomenclature. And one of those rules is that pre-existing names get precedence. It seems that the family connections of Dicentra spectabilis had long been suspect and that as early as 1850 a published article had given it a different genus name. That name? Lamprocapnos.

While we may grouse about the genus name of this plant, everyone is agreed that the species name, spectabilis, which means spectacular or showy, is apt! Whatever we call it, this wonderful spring bloomer is likely to remain a garden favorite.

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46 Comments leave one →
  1. October 28, 2012 8:38 pm

    Jean,
    Wow that’s a lot to take in! It’s sometimes
    difficult for me to remember the botanical names and now even more so with the change. It will take some getting used to, but I understand and it makes complete sense. I’m sticking with bleeding heart for now! Great post as always.

    • November 4, 2012 10:14 am

      Sandi, I have an easier time remembering some than others. Plants that I didn’t start growing until after their genus name changed are easier for me — so I have no trouble remembering that Cimicifuga has become Actaea. On the other hand, I have a lot of trouble remembering that my Aster laevis is now Symphyotrichum laeve. Mostly I just use the common name or the botanical name as I remember it and then look it up when I need to be accurate.

  2. October 28, 2012 9:58 pm

    My heart bleeds over this one! You did a lot of research, and It all makes perfect sense — to a scientist! Lets hope they can get the names changed that need to be changed and leave it that way.

    • November 4, 2012 10:16 am

      Deb, I find it easier to accept the changes when I understand the reason for them.

  3. October 28, 2012 11:01 pm

    I don’t buy it! The taxonomists make the rules, then they say: sorry, we have to follow the rules. Lamprocapnos indeed!

    • November 4, 2012 10:18 am

      Jason, Can you say “Lamprocapnos” 5 times fast :-) ? This may be an incentive for some gardeners to grow the native North American bleeding hearts, which are still Dicentra.

      • November 4, 2012 10:55 am

        Maybe, but I really prefer the old fashioned D. (or L.) specabilis, the natives seem drab by comparison.

  4. October 29, 2012 3:32 am

    To me it will always be Løjtnantshjerte, lieutenant’s heart, since my grandmother once showed me how – by careful dissection of the flower – it reveals in turn a bottle and a pair of shapely female legs. -Supposedly all that an army officer would care about… (Well, that and presumably guns, but guns have no place in a flower, no matter what the NRA might say.)

    • November 4, 2012 10:21 am

      Soren, I’m enjoying learning about all the common names for this plant. This one is hilarious! The variety of these common names reminds of us why we really do need botanical names for clear communication — even if the dang taxonomists do keep changing them!

      • November 5, 2012 2:36 am

        We definitely need a scientific nomenclature for plants, as well as the enherited common names, however many options for misunderstandings they give us. Plants that I inherit will – to me – mainly be thought of by their common names, and others will be 50/50, depending on the context.

        All science evolves, new learnings are incorporated into the taxonomy and we should be greatful that there are people working dedicatedly on increasing understanding of the plants that the rest of us “merely” enjoy. (While still giving a nod of respect to Carl Linné who perhaps more than anybody helped make the naming of plants a scientific matter.)

  5. October 29, 2012 10:18 am

    Hmm, on this occasion it seem justified, however four decade of educating myself to memorise all these names. I was even less happy to find that my favourite plant is now no longer a Cimisifuga.

    • November 4, 2012 10:23 am

      Alistair, I suspect that’s another change that’s been hard for a lot of people to take. Actaea is certainly easier to say and remember — but we put so much effort into learning to say Cimicifuga!

  6. patientgardener permalink
    October 29, 2012 2:59 pm

    I find botanical taxomany very interesting. I spent a day last year at Oxford Botanical Garden learning all about it. Whilst Linneaus sorted plants according to the number of stames now, as you say, with the technology available the botanists can examine and explore the plants far more. We spent time looking at keys to plants where you start with the stamens and then go through a whole list of questions which lead you to the right plant name. It is really interesting.
    As for the moaners – some people never like change regardless of the reason behind it

    • November 4, 2012 12:05 pm

      Helen, I would love to take a course like this with a hands-on approach to botany and taxonomy; book learning can only take me so far.

  7. October 30, 2012 4:10 pm

    That Osteospermum is now Dimorphotheca because of DNA, I can happily live with. That our thorn trees of Africa, the acacias – have lost their Latin name to the Australians, because they have more species of wattle – huh, those taxonomists break and bend the rules when they want to. (Someone pointed out that the acacias on the Nile are in the Bible)

    • November 4, 2012 12:08 pm

      Diana, I’m sorry to hear about your acacias losing their name. I think another one of the taxonomy rules may be that changes are made in such a way to preserve the genus name for the largest number of related plants. Thus, even though Dicentra spectabilis was by far the best known of the Dicentra genus and the one most important to gardeners, keeping it as a Dicentra would have required renaming all the other species in the Dicentra genus.

  8. October 30, 2012 4:29 pm

    Thanks for the comprehensive explanation – I don’t have a problem with names changing, if it means filling in missing pieces of the puzzle.

    • November 4, 2012 12:11 pm

      b-a-g, I agree with you. While I may find some name changes difficult to learn or emotionally difficult to accept, I’m committed to the project of scientific understanding.

  9. October 30, 2012 6:31 pm

    Interesting post Jean. Obviously there’s a lot of research that goes on before a name gets changed. Although count me as one of the grouchy ones as it takes me so long to remember even a few of the latin names that when they change them it’s a major setback for me.

    • November 4, 2012 12:16 pm

      Marguerite, I got the sense that the authors of the Liden et al. article knew that people were going to be grouchy about the renaming of Dicentra spectabilis — thus their explanation of why it had to be done. (Maybe one or more of them were gardeners who found themselves feeling a bit grouchy about it!).

  10. October 31, 2012 8:13 am

    Fantastic post.very informative and interesting article.thanks for mass explanation. i like it.

    • November 4, 2012 12:17 pm

      Thank you for visiting and commenting. My goal was indeed to provide an interpretation of the scientific literature for a lay audience, so thank you for your kind words.

  11. October 31, 2012 9:40 am

    As a GCA Horticulture Judge I must be mindful of the science of naming plants and be knowledgeable about the Botanical names and go along with the renaming, but as others have mused – I don’t have to like it! It is difficult when trying to properly identify a plant for show to know about all the changes. The reference books are big and unwieldy but so much easier to use than the internet which is not always reliable. But then the reference books are not so up to date on these changes that come along frequently!

    • November 4, 2012 2:37 pm

      Jayne, I have found that most of my reference books are out of date on these taxonomic changes. Do you have particular reference books or particular web sites that you find particularly useful for keeping up with the changes?

  12. October 31, 2012 3:37 pm

    I actually welcome the changes, even if it takes my aging brain a little while to adjust to the new names. There are so many species in nature that I believe have been misclassified using morphology and the Linnaean system, that molecular methods can now correct, so the perfectionist in me welcomes the improved accuracy. I agree though, Dicentra rolled off the tongue much more easily! The only downside to all of this, for me, is a substantial amount of what I’ve learned over the years, from plants to animals to microbes, even dinosaurs, is now wrong!

    • November 4, 2012 2:38 pm

      Clare, It raises the question of which is more difficult for the aging brain — learning the new stuff or unlearning the old stuff!

  13. October 31, 2012 5:27 pm

    Ugh! That’s all I can say. I like Latin names for their accuracy but I think I’ll stick with Bleeding Heart for it’s beauty and simplicity.

    • November 4, 2012 2:41 pm

      Tammy, I know what you mean. Lamprocapnos seems like such a particularly unattractive name for a particularly beautiful plant. Of course, I realize that this is a culture-bound interpretation. There may be some languages in which those explosive p sounds are the sounds of beauty.

  14. November 1, 2012 4:25 pm

    While the official name may have been changed, I think it will be quite a while before it’s ever sold under anything but Dicentra or Bleeding Hearts. I still consider it to be “Lady In A Bathtub,” the name my grandmother used. Thanks so much for the explanation!

    • November 4, 2012 2:43 pm

      Karen, This is a particularly charming common name that I hadn’t heard before.

  15. November 1, 2012 10:07 pm

    Thank you for expressing an opinion that I no longer have the energy to expel from my own lips. Grant me the serenity to accept the things I cannot change. Today I just do what I’m told.

    • November 4, 2012 4:49 pm

      LOL, Reed, I love your revision of the serenity prayer.

  16. November 1, 2012 11:42 pm

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  17. November 2, 2012 3:36 pm

    Like every other word in our gardening lexicon, if we repeat the new name often enough, we might get used to it. Thank you for such a well researched post.

    • November 4, 2012 4:49 pm

      Good advice, Allan. Lamprocapnos, Lamprocapnos, Lamprocapnos, Lamprocapnos….

  18. November 2, 2012 6:41 pm

    I suppose as humans we must be able to identify something so we can talk about it, refer to it. It is still a lovely plant with color and style.

    • November 5, 2012 1:10 pm

      Michelle, Since this plant has many common names and there are quite a few different species known by the common name of “bleeding hearts,” we clearly need some standard scientific nomenclature to specify what plant we are talking about. I agree that, by any name, this is a beautiful plant.

  19. November 2, 2012 7:21 pm

    Long-term, I appreciate the work that’s going into sorting out the botanical universe, but the process doth cause some local confusion and incomprehension. Our big California flora, the Jepsen Manual has just undergone a major rewrite, dragging along with it a re-naming of many of my favorite wild and garden plants. When just the species changes, I stand a chance of recognizing what the species was/is. But one of the big mind-wipes affected one of my favorites, deerweed, formerly Lotus scoparius, now Acmispon glaber. I might end up calling it “deerweed” for a while until I readjust! (Interestingly, all of our native bleeding hearts are still in Dicentra; in fact two species from other genera got moved INTO the genus. I guess they needed the room and decided spectabilis had to go…)

    • November 5, 2012 1:21 pm

      James, I didn’t realize that some additional plants have now been discovered as part of the Dicentra “clade” and moved into the genus. Are they plants that were not originally classified as Dicentra because they don’t have the characteristic “two-spur” flower shape? I guess it’s when a major reference like the Jepson Manual gets revised that these changes that have been accumulating in the scientific world find their way out to the gardening world. I was interested to discover that by the time I became familiar with the plant Dicentra spectabilis, planted it in my garden and learned the name, that name had already been obsolete for several years!

  20. November 3, 2012 5:52 pm

    Jean I love learning how this all happens and I expect many more changes as they explore more plants…I would love to be able to pick better names though…looks like I may just use the common names again.

    • November 5, 2012 1:23 pm

      Donna, I love learning this stuff, too. I’m already putting a college-level botany course on my “to-do” wish list for after I retire!

  21. November 3, 2012 8:35 pm

    It is becoming obvious to me that I need more resources for identifying and remembering the Latin names of plants. Many of the books I have in my collection list all the old names, which have changed dramatically in the past year or so. I agree Dicentra s. seemed perfect for Bleeding Heart. The rational part of my brain can understand the change, but the emotional part is sad about it.

    • November 5, 2012 1:27 pm

      I have been using the USDA plants database more and more as my basic reference on plant names. Usually, if you search under an obsolete botanical name, it will send you to the listing for the new name and give the old one as a synonym. I also love the way they show you the classification through all the layers of the taxonomic hierarchy.

  22. November 21, 2012 8:17 pm

    Hello Jean, I put an asterisk in my brain to come back and read the long article. But for, as one said, “my aging brain” it somehow slipped off! haha. I love the way you wrote it, and i ended up reading all the comments plus your replies. I love it when more gardeners and bloggers try their best to use the Sci names, to lessen the mistakes. I recall when i am just starting blogging, i used to privately correct some ID or the proper way of writing the Sci names, most especially my blogging friends. I am already fulfilled that at least i’ve influenced 3 of them! I stressed that Sci names no matter how difficult is necessary to remove confusion, because everybody makes a common name for their favorite plant.

    Do you know that our tomato has changed 3X since i was in undergrad years! Imagine that, and it happened while I am still alive. But i am grateful for the advancement in molecular genetics, which makes classification more reliable. It is just that we need to delete the imprints in our brains and make some new one. I was talking to a spider expert yesterday in FB, and realized there’s a lot of spiders still unclassified. So they are making the species from the country easier to remember by using our language as the root word.

  23. December 10, 2012 4:41 pm

    Hi Jean, I’m never going to remember lampra..? I’ll just have to refer to it as “the plant formerly classified as Dicentra”. It’s very difficult to undo and change what you taught yourself isn’t it? Anyway, thanks for enlightening me, as I have a few formerly Dicentra plants I’m going to have to make sure this information sticks.

  24. December 28, 2012 10:55 am

    Jean

    That’s a splendid post! I’m sorry to have been away from your blog for a while and to have missed fascinating, informative stuff like this. I was one of the commenters who bemoaned the loss of dicentra as a name, so it is very helpful and somewhat reassuring to learn more on how it came about.

    I may have recommended this before, but the Royal Horticultural Society’s plantfinder is great at helping you locate up-to-date names: http://apps.rhs.org.uk/rhsplantfinder/ Just search for dicentra spectabilis – or bleeding heart – and it will take you straight to lamprocapnos…

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