A few weeks ago I was doing a little research on a glorious plant well known to all, the dandelion. As always, when I write a text for this blog or when I prepare material for teaching, I validate the Latin names on Plants of the World Online or on Canadensys (for native and introduced vascular plants of Canada). I know the Latin name of the dandelion, Taraxacum officinale: this verification was supposed to be only a formality. I’m already eager to move on with the rest of my work when Oh! Surprise! My dandelion is not there!
Finders Keepers… well, Almost!
The computer tells me that Taraxacum officinale does not exist! What? It suggests another name. That’s when I pull out my detective’s magnifying glass to unravel the mystery: what happened to my dandelion?
First described (well, we’ll see about that later) in 1780 by German botanist Friedrich Heinrich Wiggers, the dandelion has been known and used for millennia. It’s already known to be widespread throughout Eurasia. It’s in his fabulous book Primitiae florae Holsaticae (Primitive Flora of Holstein, Holstein being a region of northern Germany) that Wiggers describes the plant in botanical terms, in Latin, of course! The Taraxacum officinale was born! According to the conventions of the Code of Botanical Nomenclature, the first to describe a plant in Latin is the proud holder of the “trademark” and therefore holder of the Latin name that will be used to name the plant, everywhere in the world. That’s something! Wiggers had just won the honor of naming one of the most universal plants on the planet: our good old dandelion, Taraxacum officinale!
But Oh! Scandal in the house! Our dear Linnaeus, father of the binomial nomenclature, had already described this plant… under the name of Leontodon taraxacum! Yes, it figures in the second volume of the Species Plantarum, published in 1753. So… logically, the real Latin name for dandelion should be Leontodon taraxacum.
Two hundred years later…
How can we explain this major fault? (We’re having fun here. It’s not that dramatic, actually) Like an elephant in the room, the subject has been avoided for over 250 years! Wiggers won over Linnaeus! And no one objected! Perhaps is it because the genus Taraxacum has become very important with its 2,458 recognized species. Yes, you read correctly! Our dandelion is not unique! It has many, many cousins spread all over the world! The entire northern hemisphere is covered in dandelions of all kinds. It seems absent only in desert regions. And I can confirm to you that it grows at more than 13,000 feet of altitude, to have crossed it there. In fact, Canada has 14 recognized species of the genus Taraxacum.
A Matter of Bracts
It may also be because other specimens of the genus Leontodon are quite different in appearance from dandelions. The flower stalks are thinner and longer. This can be seen clearly with the naked eye, even if you are not an expert!
Could Linnaeus be wrong? How to circumvent the rules of the Botanical Nomenclature Code? In 1985, we dared and we decided: our domestic dandelion looks much more like an actual dandelion (Taraxacum spp.) than a hawkbit (Leontodon spp.). What a relief!
In fact, these two genera are distinguished by the observation of the bracts under the flowers. Bracts are small scales that originally form the flower bud. When the flower is in full bloom, they can be observed under it. In dandelions (Taraxacum spp.), there appear to be two rows of bracts, one curved downward and the other erect. Hawkbits (Leontodon spp.), also called fall dandelions, have only erect, slightly overlapping bracts.
The Dandelion… More Complex Than you Think
Unfortunately, it was too early to say “Mystery solved!” The incredible diversity of dandelions has given numerous headaches to many of the world’s leading experts on the genus Taraxacum. Here the bracts are like this, there the plant is polyploid. That’s without mentioning the genetics and mode of reproduction of dandelions (I’ll spare you the part on apomixis and microspecies). The only conclusion on which botanists agree is that the common dandelion, as gardeners around the world know them, is not a single dandelion. There are hundreds, if not thousands of different species!
Faced with the insoluble ambiguity of this plant, which is nevertheless so common, our dear scientists have proposed to create an infraspecific category, a section, grouping together the different forms and origins of our dandelion… and abandoning the officinale epithet. Then, they devoted themselves body and soul to find the perfect name for this new group: Crocea, Ruderalia, Vulgaria … nothing suited perfectly. And that’s how they arrived at a result. The correct name (for now) would therefore be Taraxacum sect. Taraxacum.
Rest assured, our precious botanists know well that their entertaining name changes exacerbate gardeners and horticulturists. And on that subject, we gardeners are protected by the Code! Because it ways “that it is necessary to avoid changes of names which could create errors or plunge science into confusion”. Thus, the non-scientific community can continue to use Taraxacum officinale and that’s fine! Till then, I will keep my popcorn handy and wait for the next round of botanical nomenclature arm wrestling!
Gee, I am not certain if I dislike it more or less now that I am more acquainted with it.
Again, WOW! I have more Hawkbits (Leontodon spp.) in my year then dandelions (Taraxacum spp.), but dandelions (Taraxacum spp.), grow wild on my father 30 acre farm twenty miles north of my house. Also dandelions (Taraxacum spp.), is a big nectar flow plant for pollinators.
But dandelions lack some essential amino acids for bee health according to experts. Of course bees will go to anything if there is nothing else in bloom so they don’t starve and until they can find blooms with all the essential amino acids. I will try and find the reference to post.
This is a wonderful article because it begins to address “speciation”, which is a plant’s ability to adapt over time (usually a long time) to different kinds of habitats…this is what creates biodiversity, which is what makes our planet such a varied and interesting place, and why, promoting a species that is introduced in a wide variety of places that can overwhelm and hybridize with the species that are there might be a real problem for the animals that depend on native plant to survive.
Humans are moving plants around the world at an unprecedented rapid rate (primarily by accident but also for their own delight and entertainment) without consideration to what happens to the biology of these areas when those plants get free from cultivation.
When we talk about “the Anthropocene Extinction event” (loss of plants and animals that can reproduce freely in the wild) the rapid exchange of biological organisms by planes, trains, and automobiles, one of the major reasons is the failure of us to recognize, value, and protect the unique assemblages of the indigenous plants in the places we live.
Plants are truly what give places around the world their different identities, and in my mind one of the reasons travel is so interesting and exciting, is because the plants that evolved there also support the unique animals that live there, which co-evolved over vast amounts of time. I study the dependent relationships between animals and plants and think we need to more deeply understand the nature of the plants and animals we so casually promote and spread around or risk losing our biodiversity to a few dominant plants such as the dandelion and its many introduced non-native look-alikes.
I watch our wild strawberries disappear under a crowd of introduced plants with great concern, because they support 60 (or more) species of animals (including people, they still are the best tasting strawberry there is). They were once abundant and now are not due to the introduction of plants, such as mouse eared hawkweeds (Pilosella). These are small plants most people don’t distinguish from dandelions and they can displace the wild strawberry by a number of means, such as sub-soil chemical changes that suppress the growth of other plants, physical crowding out, and pollinator diversion. They also have more energy to devote to making room for themselves, as the animals that usually keep their populations in check where they are native were not introduced with them.
Many animals survive by eating leaves of plants. It is not just about bees. Plants defend themselves by creating defensive biochemistry, which the leaf-eater evolves to tolerate, and over time, the animal becomes specialized to eat only that kind of plant, with specialized mouth parts and body chemistry. It cannot simply decide one day to eat a different plant, so if that plant disappears, the animal goes with it.
Since 93-96% of our songbird populations, and many other animals depend on folivores (leaf eaters, mostly caterpillars of thousands of species of moths) for their protein-rich food supply to make their babies, we might want to reconsider our enthusiastic support for a widely invasive plant simply because “bees use it”. Many of the bees that use dandelions (including the introduced honey bees) are “generalist species” that fly around and eat plant nectar which is pretty generic chemically (but not always). When they do this, they fertilize the plant and allow for its survival, so when bees use an introduced plant instead, the plant the specialized caterpillar eats does not reproduce. So we lose the plant, and animals that need it for survival.
We could cling to our cultural emotional attachment to dandelions and keep blowing them around, or we can take these new revelations and protect the planet’s biodiversity. I blow asters and goldenrods, because I know how much these (beautiful and diverse native plants) support my local ecology. I love the evolved uniqueness of the plants and animals where I live. I set out (at 15) to learn all the plants in the wild, and find that a MASSIVE number are introduced (25-30%). I am 60 now, and places I have watched all my life have changed substantially, also due to introduced insect pests which are now decimating the forests. These are big problems on the magnitude of and potentiated by climate change.
A number of introduced plants are invasive (nearly impossible to remove once established and growing unchecked), the cumulative impact of which is unknown, but clearly not good, so I work to remove them in my garden (without chemicals if at all possible). I would argue that the common dandelion is one. I dig them out by hand. And I have a yard full of native insect eating birds, such as colorful warblers (who never visit plastic bird feeders), because I made room for native species and defend the plants that have always been there. They are far more interesting than dandelions and their songs amazing.
There are many places (mostly disturbed by humans with machines) where I live where there are now, zero native plants, and it is not a surprise to me that birds, and especially migrating birds, that evolved to eat native plants that provide food along many stops over thousands of miles who are now not finding what they need to complete the trip, or enough nutrition to reproduce. These are not the only reasons birds are struggling, but a basic and important one, and I love knowing I am helping. I can see the results in the numbers and kinds butterflies too. “Know thy plants” better…because they are more than decorative or useful to people.
So true Marian. Too many people do not take the time to read the science scholarly articles before they plant something. There are many more nutritious spring ephemerals and other soring plants out there if people would only plant them and get rid of the dandelions. The bees are happily in my snow drops and Mertensia virginica. Sadly it’s almost impossible to find native viola —rich in food for the bees.
Concepts like trophic cascades really ought to be talked about and taught to more people. Many folks have absolutely no idea how incredibly far reaching one simple alteration to an ecosystem can potentially have, and how it can effect things in ways that many would never be able to predict.
Fascinating story, Julie.