Colorado Dispatch: Is That A New Plant Species In My Backyard ?
The Wonder of Wildflowers in an Age of Variants
“The question is not what you look at, but what you see.” Henry Thoreau (1851)
The odds are much against finding a novel flower species in one’s backyard. Across America’s 2.4 billion acres, less than a dozen new flowering plants are identified annually according to the Missouri Botanical Gardens which tracks the discovery of new species. That makes the chance of getting lucky on any given acre no better than about 1 in 200 million.
Who beat the odds? They are typically trained field botanists. In 2021, for example, one team found a previously unknown moonwort (a small fern with half-moon leaflets) in eastern Colorado. In 2019, a Missouri Garden botanist identified a new Trillium in Georgia. And, in 2014, a prickly weed-like relative of the tomato near Valentine, Texas was found to be a new species.
A few Summers ago, I sensed that I might have won the lottery too. I had spotted a small and wholly incongruous type of milky-white bluebell that resembled a flower commonly known as Parry’s Harebell (Campanula parryi). Within a few weeks, this solitary white bell flower was joined by a flourishing colony of identical plants at the edge of the picturesque meadow surrounding our house.
This was an exciting development. Our house sits in the Crystal River valley 8000 feet above sea level in western Colorado. I had been chronicling local wildflowers for several years, although I was anything but a trained botanist. Even so, I had begun to distinguish between the familiar and the unusual, and these white bell flowers — the blooms are ordinarily lavender or violet colored — were unique so far as I knew.
[NOTE: All photos © 2022 Gregory C. Staple unless otherwise stated.]
Elation prompted speculation: Perhaps it was not the end of the natural world as we know it. Perhaps nature can still conjure new marvels despite an ongoing climate-driven apocalypse. (see e.g., The Sixth Extinction by Elizabeth Kolbert.)
I also tried out names for this soon-to-be-born species, though well aware I was getting ahead of things. I wanted to christen it for my mother, a retired biology professor, who had long encouraged me to pay more attention to flora and fauna because, unlike my parents, I had forsaken science for more prosaic fields (the law and, later, business). Hence, when it came to gauging new plant species, I was a complete neophyte.
What I lacked in credentials, however, I hoped to make up for in curiosity. And persistence. That proved essential because I soon found that determining a new plant species in the early 21st century is anything but straightforward. I should not have been surprised.
In 1845, Alexander von Humboldt, the renown German naturalist wrote: “Each step that we make in the more intimate knowledge of nature leads us to the entrance of new labyrinths.” A British contemporary of von Humboldt, William Blake — he who saw “a World in a Grain of Sand, and a Heaven in a Wild Flower” — had a similar view. “In the universe there are things that are known, and the things that are unknown, and in between there are doors,” wrote Blake.
I soon knew what they meant first hand.
A Chance Discovery
My story began in the Summer of 2018. When idly walking through the meadow behind our house, I noticed a small, singular white flower just inside a willow break that bordered a neighboring wetland. It was a delicate upright bloom about the size of a large sowing thimble with five pointed petals and a prominent white pistil. Its thread-thin stalk barely held it aloft some eight inches above the ground.
I could not identify the bloom in any of the half-dozen wildflower guides I owned. The flower seemed to resemble the handful of lavender-colored Parry’s Harebells that grew elsewhere on our property. Yet, the closest of these was some 40 or 50 yards to the east. I did not think that this solitary plant might be related and, after another month, I could not find it again amid the tall meadow grass.
But nature persisted. The next Summer, in mid-July, I noticed the same pale flower. It stood alone as before, almost hidden in the grass, and easily overlooked next to the more florid stands of Groundsel, Oxeye Daisies and showy Checker Mallow.
It took still another year, until 2020, before my curiosity about this mystery bloom got the better of me. By then, I had tentatively identified it as a type of harebell, a cousin of the nodding violet blooms that frequently dotted other parts of our meadow (Campanula rotundifolia).
But this bloom resembled a less common species, Campanula parryi. Except it was white, not blue, like every other specimen I had ever seen.
By late Summer, I had a spreading colony of these milky-white bell flowers, each new settler nodding gently in the breeze. They were hard to ignore. I counted thirty single white blooms in mid-July; fifty-two by the beginning of August and seventy-four a bit later on.
Were these unusual flowers just a white petaled version of Parry’s Harebell? Or could this variant be entirely novel and, if so, could it be a separate species? What transforms one flower species into a new one anyway? Is it a chance mutation leading to a change of color or shape or locale? Or is something more profound — more evolutionary significant — required? If so, what is that? One question led to another. I began to enter the labyrinth.
It was now the Autumn of 2020 and it had not escaped my notice that the unexpected appearance of my backyard flower morphs was playing out in the face of the most dramatic large- scale evolutionary lesson of our time: the global spread of the SARS-CoV-2 virus and its steady mutation into numerous variants or forms.
How could the variants of a small, little-known Colorado wildflower hold one’s attention at a time like this? How not? I took refuge in Lewis Thomas’ classic 1974 essay, The Lives of a Cell.
“Man is embedded in nature,” wrote Lewis. “Our genomes are catalogs of instructions from all kinds of sources in nature… We live in a dancing matrix of viruses; they dart, rather like bees…from plant to insect to mammal to me and back again…tugging along pieces of this genome, strings from that…passing around heredity as though at a great party….“ The hard problem,” warned Thomas, “will be to cope with the dawning, intensifying realization of just how interlocked we are.”
Any Other Specimens?
To unlock my own biological mystery, however, I had to know first if my white harebells were truly unique. Who should I ask? I started with Al Schneider’s web-based guide to Colorado wildflowers as I had long found it near-comprehensive. (An app is available at highcountryapps.com.) Schneider, a retired English professor, is a tireless photographer and, along with his wife, Betty, has even discovered three new plant species. He is also an ardent chronicler of botany’s Western pioneers, much of which is shared on the web site.
Schneider says Campanula parryi, like numerous other mountain flowers was named for Charles Parry, an energetic 19th century doctor, explorer and naturalist who was known as the King of Colorado Botany. Over a span of twenty years, beginning in the 1860s, Parry collected over 100 new Colorado species (it helps to be first !). His finds included the delicate lavender bluebell that was named for him in 1886 by his friend, Asa Gray, Professor of Botany at Harvard. (Gray may have been returning a favor: In 1861, following his first ascent, Parry had named the tallest mountain in Colorado’s front range, at 14,273 feet, Gray’s Peak.)
Gray, who went on plant collecting trips with Parry, founded the Harvard Botanical Garden as well as its Herbarium. His Manual on Botany (now in its 9th edition) became a classic in the field. Grey also donated his personal collection of over 200,000 plant specimens to the university; it included many specimens gathered by Parry.
But let’s get to the point: Schneider’s web pages for Campanula parryi did not include any white blooms. Nor, so far as I could determine, did Gray’s collection at Harvard. In recent years, millions of Harvard’s specimens have been digitized — including hundreds of well-preserved plants from mid-19th century Colorado collecting trips — and can now be accessed on the Internet. More on digital herbaria later on.
I checked in next with iNaturalist.org, the popular crowd-sourced photo app for identifying plants of all kinds on the fly. Since being founded a decade ago, the iNaturalist app has become the “go-to” virtual field guide for amateur botanists and citizen-scientists world-wide. Their database now lists over 65 million observations contributed by 1.8 million participants. But, again I came up short; in mid-Summer 2021, an iNaturalist search for Campanula parryi only displayed over 200 images of blue variants.
Finally, I delved back into my favorite paper field guides, Wild at Heart by Snowmass-based naturalist, Janis Huggins and Wild About Wildflowers by Crested Butte botanist, Katherine Darrow. More negative proof. Both pictured only lavender or violet- blue specimens of Parry’s Harebell.
Darrow’s book did clear up one ancillary mystery though: How it is that mountain bluebells have come to be called harebells? Bell flowers (the Campanula genus) can be found across the northern hemisphere, writes Darrow, and are best known as the bluebells of Scotland. In fact, these flowers were once used in the manufacture of blue dye for tartans and are the symbol of the MacDonald clan.
Darrow continues: “Another name, ‘witch’s thimble’ comes from a Scottish superstition that witches commonly transform themselves into hares.” They apparently used juices squeezed from this bell flower, thus the colloquial appellation, harebell. This was the kind of esoteric aside for which good field guides are known. Engaging, yes, but it did nothing to advance my taxonomic quest.
So I reached out to another Colorado wildflower enthusiast, Karin Teague, who oversees Aspen’s Independence Pass Foundation. Teague has hiked the high country for decades and also keeps a detailed online photo-diary of the blooms she spots each Summer. If anyone was likely to find a botanical outlier in the Campanula genus, it was she. Again the answer was negative.
New Variant or Species?
I was beginning to feel more hopeful. Plainly my white bell flowers were extremely rare. Nevertheless, I wanted to dig deeper and gain a sense of how their unique coloring came about, and whether this unusual aspect might make them different enough to be deemed a separate species.
Schneider had told me that he wasn’t sure about “the cause of white-flowering variants of normally non-white-flowering plants, but such occurrences are common and I’m sure you have seen many. I have.” He continued: “My assumption on white variations is the same as my assumption on the many plant variations that one finds: normal reproductive chance variation.…. With white flower variations I would assume that the normal pigments are blocked and non-functional.”
Schneider also pointed me to a fellow traveler, Chris Helzer, the Director of Science for The Nature Conservancy in Nebraska, who posts regularly on the natural world as “The Prairie Ecologist.” Helzer had raised similar questions a few years earlier: “I want to know why many wildflowers, especially those with pink, blue, and lavender-colored blossoms, sometimes produce white flowers,” he wrote. “What’s up with that?” How do “the mechanics” work, asked Helzer.
While it was good to have reinforcement, I realized that it was time to consult with the kind of experts who might flesh out the answers that both Helzer and I sought. But, again, who to ask? Given my prior on-line sessions with Harvard’s herbarium, I settled on a like resource that was closer to home — the Rocky Mountain Herbarium (RMH) at the University of Wyoming in Laramie.
The RMH is the premier herbarium for the mountain states with over a million specimens and houses the National Herbarium of the U.S. Forest Service. It has long been curated by Dr. Burrell “Ernie” Nelson, who is on the faculty in the University’s Botany Department. I did not want to contact Nelson unprepared. After all, Nelson captained the leading herbarium for the Rockies. I was but a curious civilian.
I was also grappling with an inconvenient new fact. During an online search of RMH’s holdings (there were 266 listed specimens of Campanula parryi) I had come across a single specimen (no.17) with white flowers. It had been collected in July 2007 by one Ben Legler during a floristic inventory of Ted Turner’s 500,000 acre Vermejo Park Ranch near Raton, New Mexico. White flowers or not, it was classified as Campanula parryi.
My disappointment was palpable. But could the RMH have been mistaken? I knew that happened as I had read that specimens from prior eras were regularly being re-classified. It was time to marshal my best evidence. Perhaps there was something about my variant that was different from Legler’s. I needed a physical “type specimen” especially if I was going to plead my case with Nelson.
This was easier said than done. I had never prepared a herbarium specimen before and the only available source stock — our backyard colony of white harebells — was fast disappearing with the Summer sun. I had to act quickly or wait another full year.
My First Herbarium
The next morning I started early, armed with a rough set of instructions gleaned from a late-evening Internet session. I had also lifted any clues I could from a new history of pressed plant collections that I had recently acquired: Herbaria, by Barbara M. Thiers, the long-time Director of the New York Botanical Garden. The evocative color plates of classic wildflower specimens had made Thiers’ 2020 book an immediate favorite. Page after page brought the heyday of Victorian collecting trips to life, inviting the reader to join that exclusive club of botanical pioneers who, like Parry and Gray et al, had amazed their peers with new discoveries. All one needed were enough eye-catching specimens.
With trowel in hand, I dug carefully, unearthing several white flowered samples, all with root hairs, leaves, stems and flowers fully intact. I also collected some violet harebells for comparison. The soil was drier than I had expected and the roots yielded more easily than anticipated.
Once gathered, I laid everything out on sheets of ledger-sized (11”x 17”) paper, careful again to ensure that every aspect of my specimens would be clearly visible once pressed flat. Lacking a proper plant press I improvised, drying the plants by overlaying parchment paper interleaved with cardboard for aeration. I then weighted my “flower sandwiches” on a large worktable using thick, old planking from our store shed.
During the next couple of weeks, while waiting for the specimens to dry, I worked on mocking up appropriate labels. I knew that herbaria are quite particular about this and I adhered closely to convention. An acceptable label should state the Family, Genus and Species for the specimen; the altitude and geographic coordinates where it was found (and the source of this data — e.g., using GPS); the associated town (or county) and state; the date of collection and the collector; and, lastly, when the specimen was identified (i.e., formally classified) and by whom. As noted earlier, the person identifying a specimen is often quite different from the one who gathered it.
Two weeks later, with my new set of labels in hand, my collection had dried sufficiently to mount. Placement was key and, per my notes, I used a little glue and a set of thin paper strips to hold each Campanula parryi specimen in place. I then attached my herbarium labels at the bottom of each page. It had taken an extra month, but I finally felt ready to do business with the taxonomic gatekeepers at the Rocky Mountain Herbarium.
Despite weeks of preparation, things did not go quite as I had hoped with Dr. Nelson, the Herbarium’s chief curator. My written query failed to elicit a reply. So I phoned him one morning, quickly explained why I was calling, referred to my prior missive, and waited for some response.
There was a foreboding pause. When he spoke, Dr. Nelson was short and matter of fact in characterizing my white harebell. “I think it’s a fluke… It has no taxonomic significance.”
Then he continued in a like vein so that I could not mistake his conclusion. So far as color was concerned, he said, “generally we don’t recognize those white flowers as a new species.” And, just like that, our conversation was over. The RMH apparently had no interest in having my type specimen either.
What now? Nelson’s words were still echoing in my ears: “no taxonomic significance”. Not a new species. That was the end of it or was it?
My white flowered harebell might be a fluke, perhaps triggered by a chance mutation, but it might still be a unique and worthy of being cataloged and preserved even if the herbarium already had one such specimen. How do color differences arise in blue flowers anyway and how did Nelson know this characteristic was insufficient to mark it as a new species?
I needed a second opinion. After all, there were other authorities and other herbaria in my home state. Chief among these is the University of Colorado’s herbarium in Boulder, housed in the campus Museum of Natural History. The herbarium is curated by Dr. Erin Tripp, an Associate Professor in the Department of Ecology & Evolutionary Biology. She is also the current President of the Society of Herbarium Curators. All of which suggested that Dr. Tripp might be my best bet for a second opinion.
Before contacting Tripp, however, I decided to boost my chances of navigating her likely responses by taking a short self-study course on the genesis of floral colors. Botany 101, here I come.
What’s In A Color Anyway?
The bottom line is this: The hues we see in flowers — barn red, sunflower yellow or sky blue, for example — are mainly determined by a plant’s DNA. The detailed genetic codes embedded in the DNA dictate which pigments are produced, in which cells, when and in what amounts. When a flower is red, for instance, it means that the cells in the petals have produced pigments that absorb all colors of light but red which is reflected. So the flower appears red.
There are two major classes of flower pigments: carotenoids and flavonoids. Carotenoids include carotene pigments which produce yellow, orange and red colors. Flavonoids include anthocyanin pigments — of prime interest for Campanula parryi because they mainly yield blue and purple colors. (Anthocyanin is derived from the Greek (anthos) “flower” and (kyaneos) “dark blue”.) Thus, a reduction or absence of anthocyanins may lead to a white or paler bloom.
The visible colors derived from these pigments can be impacted by a number of factors. They include the interaction of different genes (Campanula have thousands of genes spread over tens of chromosomes), the age of a plant, seasonality, drought, the composition of soil (acidity, trace metals) and altitude (blue flowers are often a deeper violet at alpine elevations).
Flower color is a matter of evolutionary survival for plants as flowers house the plant’s reproductive parts. It is the flower that attracts pollinators, such as insects and birds, and it is for them that colors really exist because pollination, and subsequent fruit production, is the main purpose of most flowers. Bear in mind though that pollinators commonly do not see the colors we do. Some flowers express pigments that can only be seen in the ultraviolet spectrum. A flower that appears red to us may appear white to an insect. Or a white flower may appear light blue to insects.
Flower color is linked to evolution and to speciation because some colors — as seen by pollinators — may be favored over others and lead to greater reproductive success (i.e., “fitness”) for a plant. Larger populations, in turn, improve the chances for wider geographic dispersal and, subsequently, greater hybridization and mutations which may occasion new species. Conversely, when a color (or a color variant) is unpopular with pollinators, the species is likely to decline and may become extinct.
Color aside, scientists have found that the presence of anthocyanins per se may convey independent evolutionary benefits. Anthocyanins help to “mop up” free radicals — unpaired electrons — produced by environmental stresses (pests, UV rays) that can damage plant tissues. Consequently, anthocyanin can help to make a plant more adaptable.
Significantly, the benefits plants may derive from anthocyanins also carries over to our own well-being. It is why doctors recommend eating more plants rich in anti-oxidants (i.e., ones with anthocyanins such as blue berries, pomegranates, eggplant, red onions, etc.) to deter potential damage to our DNA, proteins and other critical molecules. (Note: Some scientists report that the boost in anti-oxidants these plants may provide apparently is not due to the anthocyanins as such but to their various metabolic products.)
A Second Opinion
With this color brief to hand, I was ready to reach out to Tripp. Perhaps she would have a little more interest in unusual local wild flowers. I was right, and wrong — right about her interest, but wrong in thinking my specimen might be something special.
“What a beautiful plant!” began her email. (I had included a number of photos along with my query.) “Thank you for sharing, and we would love a specimen at COLO [the herbarium] if you would like to deposit it there.” Well, that was welcome news — my specimens would now have a good home!
Pleasantries over, next came the hard science: “What constitutes a new species is a loaded question, and depends on your species concept. If you opt to follow the BSC (Biological Species Concept), it’s about whether the things could interbreed.”
She continued: “From my perspective, color polymorphisms are extremely common in the flowering plant biota of Colorado, especially in the sub-alpine to alpine. There are purple/white morphs of many many different herbaceous plants… I don’t personally view these as constituting different / distinct species [because] for the most part those forms are inter-fertile. But ultimately, whether to describe something as new is a decision by the individual / professional, and really not anyone else’s…”
Now for the genetics. “In instances where studied, purple/white morphs often can be attributed to either a cis- or a trans-regulatory mutation to the MYB regulatory loci of the anthocyanin pathway.”
That was a lot to parse though I got the gist of it (i.e., genetic mutations are likely behind a color change). I vowed to fill in the gaps — getting a better handle on “cis”, “the MYB regulatory loci” and the “anthocyanin pathway” et al — once I had time to dive into the next module of my Botany 101 course.
But while I had Tripp’s attention, I pressed for additional insights on the likely mutations involved: “How would we know,” I queried, “if there has been a mutation in the ‘cis- or a trans-regulatory domains of the MYB regulatory loci of the anthocyanin pathway’ for this morph of Campanula parryi ? [Note: “Cis-regulatory elements (CREs) or Cis-regulatory modules (CRMs) are regions of non-coding DNA which regulate the transcription of neighboring genes.]
Is there a lab in your department or at the Herbarium that might be interested in sequencing blue and white specimens of this species and providing some analysis — perhaps as part of larger investigation into wildflower color morphs ? “ I could see her reply — along the lines of ‘You’ve gotta be kidding me’ — before I even read it. Here is the text in all CAPs exactly as written:
“POSTDOCS AND FACULTY SPEND YEARS UPON YEARS TRYING TO DISENTANGLE THIS QUESTION. IT IS A MASSIVE RESEARCH ENDEAVOR. THAT’S HOW. TAKES YEARS, EVEN IN A SINGLE SYSTEM. NO, UNFORTUNATELY I DON’T KNOW OF ANYONE WHO NEEDS MORE PROJECTS, SORRY TO SAY. I WISH I COULD SAY THE ‘WHY’ BEHIND ALL OF MY QUESTIONS/CURIOSITIES ABOUT NATURE. BUT I DON’T. ERIN”
Color Chemistry: Lesson Two
Thanks largely to the perceived health benefits of plants high in anthocyanins, there is considerable research available on how these pigments are produced (i.e, their biosynthesis) and the associated genetic coding.
As Tripp had emphasized, both subjects are extremely complex, opening doors to their own intriguing labyrinths which I quickly realized are best navigated with a guide steeped in biochemistry or plant genetics, or both (i.e., someone like Tripp). Even small blue wildflowers are home to very sophisticated chemical factories that have been honed by evolution over millions of years.
Let’s start with the biochemistry. Drawing on the Wiki entry for anthocyanin and some recent articles on plant science, one learns that cells assemble anthocyanin pigments from two different streams of chemical raw materials. One stream involves the so-called “shikimate pathways”; shikimate is a type of metabolic acid named for the Japanese shikimi flower (a star anise). The other stream produces three molecules of a malonic acid derivative.
“These streams meet and are coupled together by the enzyme chalcone synthase, which forms an intermediate chalcone-like compound via a polyketide folding mechanism….The chalcone is subsequently isomerized by the enzyme chalcone isomerase to the prototype pigment naringenin. Naringenin is subsequently oxidized by enzymes such as flavanone hydroxylase, flavonoid 3'-hydroxylase, and flavonoid 3',5'-hydroxylase, These oxidation products are further reduced by the enzyme dihydroflavanol 4-reductase to the corresponding colorless leucoanthocyanidins…”
Are you lost? I was initially, for sure. But keep going because, before you get out of this maze — to the synthesis of the anthocyanins behind the observed color in the petals of a Campanula parryi — the chemical precursors must be further catalyzed by at least three other enzymes (e.g., leucoanthocyanidin dioxygenase; UDP-3-O-glucosyltransferase; dihydroflavonol 4-reductase; and so on ).” After that, sugar molecules are attached to the intermediate product “by various members of the glycosyltransferase enzyme family, for instance, flavonoid 3-O-glucosyltransferase (UFGT), and might be further acylated with aromatic acyl groups by acyltransferases.”
Whew! While I could not fully grasp this chain of events, there seemed to be one big conclusion: blue flower colors involve a pretty complicated chemistry. Which implies: Even a minor disruption in the way any of the required enzymes work — by either genetic or environmental factors — can halt or alter anthocyanin production. And genetic mutations alone may do the trick as they impact how genes are actually expressed — that is, how the genetic codes actually assemble (or fail to assemble) different chemical molecules.
It’s (Mostly) In The Genes
It was time, therefore, to journey a bit more deeply into the DNA labyrinth behind the production of anthocyanins. I hoped that would shed some light on how any chemical hiccups may arise and help to explain the technical terms rolled out by Erin Tripp (e.g. the “MYB regulatory pathway” etc.).
Scientists have found that each of the enzymes catalyzing the chemical reactions described in the last section of my study course are encoded by two types of “structural genes”: early biosynthesis genes (EBG) and late ones (LBG). ). In addition, regulatory genes are involved; they encode “transcription factors” — those proteins that initiate how genetic information from DNA is transcribed to messenger RNA — the intermediate molecular form that turns a gene in DNA into a protein in a metabolic pathway. (Again, gene “expression” involves the translation of genetic codes into instructions for building specific molecules, typically proteins.)
Now we get closer to the inner rings of the maze: The regulatory genes flagged above are “called the MYB-bHLH-WD40 (MBW) complex, consisting of MYB,” — the gene mentioned by Tripp that encodes a protein functioning as a transcription regulator — “a basic helix-loop-helix (bHLH) and WD40 repeat families.” The “[r]educed biosynthesis is controlled by downregulation of MYB activators and upregulation of MYB repressors.”
While the so-called EBGs apparently have limited impact on the production of anthocyanins, in contrast, “the transcription level of LBGs coincides well with anthocyanin content and is significantly higher in pigmented compared to non-pigmented tissues, suggesting that variations in LBG expression determine the quantitative variation of anthocyanins….”
So there you have it. Given that the chemistry leading to color variants (polymorphism) is complex, chance mutations in the “late biosynthetic genes” or in the transcription process — namely, how messenger RNA is read or expressed within plant cells, thus impacting one or more steps in the extended biochemical synthesis — may well tell the story (environmental factors aside). Al of which likely explains why Erin Tripp said what she did in exasperated CAPS.
My foray into the molecular biology behind wildflower pigments had also brought home a deeper truth. As Lewis Thomas said, when it comes to living organisms the rules of the game are much the same whether it’s wildflowers or viruses. Chance and opportunity — the nature of a host and environment — largely determine how genes play out; the scope of variation and survival; the colors in a birthday bouquet and a memorial garland.
Back to the RMH
After my rather brief exchange with RMH’s Nelson, now some weeks back, I was still curious about that single white specimen in the RMH collection and its origins. I wondered if the collector, Ben Legler, had continued botanical field work and, if so, whether he might offer another second opinion (or a third) on the species question. I had been heartened by the fact that Erin Tripp had taken a soft approach to this matter; recall her view was that “ultimately, whether to describe something as new is a decision by the individual / professional, and really not anyone else’s…”. Who was this guy Legler anyway and what did he think about that?
It turned out that, since his days cataloging plants in New Mexico, Legler had earned a M.S. in Botany, co-authored a leading field guide to Pacific Northwest flora, and become the senior Collections Manger for the RMH at the University of Wyoming. Small world! After I emailed him, Legler got back to me the same day.
“I would agree with Ernie [Dr. Nelson] that the white flowered plants you discovered, and the ones I found in New Mexico, do not merit recognition at any rank, “ he began. “They could differ from the normal, purple-flowered form of Campanula parryi by a single allele [version of a gene] …maybe an uncommon recessive allele that is rarely expressed. Or it could be a simple genetic mutation that knocks out one of the genes coding for a step in the process of creating the anthocyanic pigments that produce purple coloration. Take away those pigments and you might end up with a white flower.” Tripp had said much the same thing, of course.
But Legler departed from Tripp when it came to the species question: “A single allele or genetic mutation is not enough to create a distinct species, subspecies, or variety — I’d expect those white flowered plants to be capable of freely interbreeding with purple-flowered plants, and they would not represent an independent evolutionary lineage…. A single trait does not normally make a species. Imagine trying to use eye or hair color as a basis for splitting humans into different species.”
Valid point, I thought, but dragging Homo sapiens into the equation can make things personal — I mean, I’m not trying to argue that one color of harebells is any better than another, or deserves more botanical recognition. (At least not yet, but keep reading.)
Legler then closed with the following observation: “Occasional white flowered forms [my emphasis] can be found in many (possibly all) species of plants that normally produce purple, pink, or blue flowers. And some species normally produce multiple non-white color forms.” He then pointed me to several online examples, including a white variant of the common Campanula rotundifolia that was discovered in 2006 by Dick Gilbert and posted by the University of Washington’s herbarium.
Species: In the Eye of the Beholder or Not?
I noted that Legler had chosen his language carefully. He referred to “forms” of a species, such as Campanula parryi, having different flower colors and not a “subspecies” or a “variety” or a “variant”. No, for Legler, it was the same flower, only having different colored petals — just a different form of the same species, a difference of no more scientific (read, evolutionary) significance than a family of children some brown haired and some blond.
I knew by now that Legler’s view (not Tripp’s) was the dominant perspective. For most scientists, species are axiomatic and their definition is closely guarded. After all, taxonomy (classifying species) is the foundation of modern biology because the evolution of species (i.e., speciation) is at the root of everything that has ever been alive and drives the great chain of being — from viruses to wildflowers — that began on earth roughly 3.5 billion years ago.
Current taxonomies largely date from the work of Carolus Linnaeus, the Swedish botanist who, in Species Plantarum (1753), formulated a binomial naming system. It identifies every organism by a generic Latin name (genus) and a specific name (species) — Campanula parryi, for instance. Each genus, in turn, is part of an expanded system of ascending breadth. It is headed today by domains; then come kingdoms which devolve to phyla, followed by classes, orders, families, genera and finally species.
In defining a species, Linnaeus gave primacy to the natural attributes of individual organisms or morphology, essentially what can be perceived. For flowering plants, Linnaeus focused particularly on their sex organs and in minute detail.
As recounted in Michelle Nijhuis’ new book on the conservation movement, Beloved Beasts, his description of some flowers as “having two husbands in the same marriage” or “twenty males or more in bed with the same female” — presumably, multiple stamens — was considered scandalous. Since the late 20the century, however, morphology has been largely supplanted by the far less titillating analysis of plant genomes to order their evolutionary status vis-à-vis other organisms.
When does an organism become different enough from another one that it counts as a separate species? The textbook definition — referenced by both Tripp and Legler — is the ‘biological species concept’ or BSC. It was proposed first in the 1940s by Harvard Professor Ernst Mayr, an influential zoologist and former curator at the American Museum of Natural History. The BSC holds that species are “groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups”. In short, two organisms are the same species if they can breed and produce fertile offspring.
The BSC definition is designed to ensure that each particular species represents a distinct (i.e., unique) evolutionary lineage. Nevertheless, in practice, this definition has long been problematic.
How do you determine that two seemingly alike organisms — for example, a lavender and white variant of Campanula parryi, especially if gathered in widely separated locales — can actually interbreed? And, how important is fertility to the determination if each variant also can reproduce asexually, e.g., by cloning through its own rootstock or rhizomes (known as vegetative reproduction) which is the case with Campanula parryi ?
Consequently, in the field, BCS requires close observation, commonly over years. Few of Colorado’s 19th century gentleman botanists, such as Parry or their compatriots in other unexplored climes, had time for that. They typically gathered thousands of species on a collecting trip and left it to others, primarily “desk taxonomists” (such as Harvard’s Gray who, as noted earlier, “identified” Campanula parryi) to sort their bundles of specimens.
Some identifiers tended to lump together specimens that appeared nearly identical; others split species based upon the smallest differences including sometimes color variation. A prominent example is the native blue Columbine (Aquilegia coerulea), Colorado‘s state flower, whose genus (named for petals like eagle wings) is now split into at least 70 species. Many of these were only recently confirmed using DNA analysis.
According to a photo-rich history on the US Forest Service’s web site, Columbines migrated over the Bearing Sea land bridge at least 10,000 years ago and quickly radiated throughout North America. New species with different colors — white, yellow, cream, pink and red — arose with different positions for presenting their flowers, sepals, and spurs, and different spur shapes largely in response to their primary pollinators, such as hawkmoths, bees and hummingbirds.
However, one leading authority (Floras of North America ) holds that many species of Aquilegia remain polymorphic. They vary, for example, both in color and the shape and length of their petals. (Aquilegia coerulea is one of those with petals from blue to white, and with different spur lengths.) This makes any given Aquilegia species difficult to define.
Some of the variability apparently is due to what biologists call introgression — the transfer of genes due to hybridization and repeated backcrossing. Floras reports that “even distantly related species of Columbine are often freely inter-fertile, and many cases of natural hybridization and introgression are known from North America.“
On these facts alone — and the evolution of tens of other genera is filled with like stories — one can understand the motivations of both “splitters” and “lumpers.” In her classic 2009 history of taxonomy, Naming Nature, Carol Kaesuk Yoon put her finger on the deep emotions involved: “To give a thing a name, to pull it out of the cornucopia of life and put your own personal stamp on it, to say I name you such and such and therefore declare things existence and its place in the natural order is a powerful thing.”
“Never mind,” says Yoon, that evolution has made it clear that a species could never be a discreet, definable thing.” (viz Aquilegia. ) “It was just a momentary segment of an ever growing branch on the tree of life…like trying to capture, in words, a moment in time, a bit of the flow of a river, a thing that by its very nature was ever-changing and had no clear beginning or end. “
Indeed, even Charles Darwin, who made speciation central to evolution — famously described as descent with modification of new species from earlier ones, driven by natural selection — thought it was a fools errand to try and pin down exactly what made one organism a distinct species rather than just a variant. The Origin of Species, published in 1859, includes this notable passage: ”Compare the several flora of great Britain of France or of the United States, drawn up by different botanists and see what a surprising number of forms have been ranked by one botanist as good species and by another as mere varieties.”
Of the term species, Darwin wrote: “No one definition has yet satisfied all naturalists; yet every naturalist knows basically what he means when he speaks of a species.…” Similarly, “the term ‘variety ‘ is almost equally difficult to define; but here community of descent is almost universally implied though it cannot readily be proved.”
To move beyond the old debates, some working naturalists have begun to advance a less preclusive view of species. One of these (and Erin Tripp may be another) is Richard Pyle, a Hawaii-based naturalist who is an expert on sea corals. “My school of thought,” says Pyle,“ comes from the idea that evolution doesn’t produce species …evolution produces populations of organisms that have different levels of interbreeding with each other over time.” Pyle adds: “Those populations change over time because of climate change and other circumstances. It’s just a kind of amorphous mix of things that definitely cluster but don’t necessarily have hard boundaries between species.’”
Celebrating Diversity, However Named
Let’s get back now to the main story. With a nod to Darwin, why not simply celebrate Campanula’s white color forms, new species or not, and leave it at that? Why stay fixated on the species thing? I had two main reasons, one admittedly selfish, and the other linked to my initial thinking about biodiversity.
First, as anyone who has ever spent much time outside knows, the natural world is full of unexpected wonders and, as Yoon candidly wrote, the thrill of discovery — of finding something that nobody else has spotted — can be heady stuff. This is especially so when one’s own patch of nature has been well picked over for centuries.
Moreover, if some novelty you have found passes scientific muster as a new species then you get naming rights. The accepted rule book for naming plants (i.e., the International Code of Nomenclature) bars one from labeling the find after yourself. Friends, relatives, pets, etc. are fair game though. Finding a novel species therefore offers the chance for a kind of immortality — a chance to name a historic twig, no matter how small, on that enormous ever-branching tree of life which has been evolving for billions of years.
Naming a species also gets you immediate scientific recognition. Globally. New species are added to the world’s official plant lists (see the plantlist.org). Herbaria around the world may ask for a type specimen. Notably, over 63 million specimens can now be searched at iDigBio.org.
Finally, new species become nouns. New color morphs are nameless, subsumed under the names of others. Species become part of the known world. Color morphs are comparatively invisible. True, some may also be preserved, to record the variation within a species, but they typically get second billing.
My second reason may have more resonance for some. It is certainly more pressing in the face of the ongoing extinction of so many species. How do you conserve what you can’t define or measure?
Species have long offered science and governments with a fairly bright line concept, a concrete means to both measure and protect the word’s diverse life forms. In the U.S. (and internationally), the law offers a measure of protection for species that are deemed “threatened” or “endangered”. For example, lists of at-risk or “sensitive” species are maintained by the Fish and Wildlife Service as well as the Forest Service and Bureau of Land Management. and some private actions which may harm a listed species are generally prohibited; for non-listed species there is no such protection. (See, for example, this proposal to designate a critical habitat for the endangered Tiehms Buckwheat which is unique to the site of a proposed Nevada lithium mine.)
Similarly, on a global basis, the International Union for Conservation of Nature (ICUN) maintains a “Red List of Threatened Species”. It now covers 40,000 organisms or 28% of assessed species. The list ranks species from “secure” with abundant numbers and no major threats to “critically impaired” which typically have five or fewer occurrences.
All of this seems to argue for doubling-down on the discovery, naming and classification of as many new species as we can. And yet and yet, in an age of mass extinctions, my own experience suggests that a fixation on species alone may dilute our efforts at preserving biodiversity whether or not a plant is actually at risk. For example, when a new species of flower is identified, no special consideration typically is made for its polymorphic characteristics. This seems to be especially true for color, as with Campanula parryi.
When the common form of a wildflower is blue or purple, should white variants have special protection? Or only as part of a wider scheme that protects the more common form? And if it is the latter, what we will be missing?
Recall that the anthocyanins that give blue wildflowers their hue may offer protection against various environmental stresses. This may help to explain why white variants are comparatively rare. But might such variants then be more likely to harbor off-setting mutations that yield novel biochemical products with similar restorative benefit to anthocyanins. And, in time, might such benefits make the white form more resilient than its blue siblings? Further, could the chemistry underlying that resilience have wider health benefits for our species, as with the metabolism of anthocyanins?
Speculative? No doubt but if new forms of a species — dare I say variants (a/k/a latent new species) — have no independent status or protection, are we being short-sighted In terms of biodiversity? How would we know?
Questions like these have made me increasingly partial to ecological or habit-based approaches to protecting biodiversity. To be sure, under our existing laws, habitat protection is at the root of many measures that are taken to protect or mitigate adverse impacts on at-risk species. (See the proposed Tiehms Buckwheat habitat designation, above.) Yet, this is still a species-first approach.
I am also partial to the new research questioning the primacy of individual species per se as detailed by Merlin Sheldrake in his provocative 2020 book, Entangled Life. Sheldrake highlights recent learning about the world of fungi, lichens and microbiomes — research that is changing our perspective about where one organism or species ends and another begins.
The more we look, writes Sheldrake, the more it appears that many plants and animals are in fact complex ecosystems “composed of — and decomposed by — an ecology of microbes, the significance of which is only now coming to light.” Beyond that, “more than ninety percent of plants depend on mycorrhizal fungi — from the Greek word for fungus (mykes) and root (rhiza) — which can link trees in shared networks, sometimes referred to as the ’wood wide world’ “.
Sheldrake had me thinking anew about whether I had the full story about the origin of those white harebells in our yard. Was the differential biosynthesis of anthocyanins, perhaps due to some unknown mutation that impacted one or more enzyme, the whole story? Or was there more?
What about the unseen mycorrhizal networks in the soil that might link one harebell to another, blue and white alike? Or the links between each Campanula parryi and the many other meadow species nearby which include a variety of willows, grasses and flowering perennials? What role, if any did these hidden networks play in birthing new forms or variants? And what about the unknown bacteria (and viruses) within those plant communities?
I have no answers to these questions as yet. I’m not even sure how to go about finding them. For now, I have settled on trying to keep all the options open and protecting this rare colony of harebells for the future. It may be a small way of making amends.
As Elizabeth Kolbert wrote in The Sixth Extinction, each day “in the amazing moment that for us counts as the present, we are deciding, without quite meaning to, which evolutionary pathways will remain open and which will forever be closed.”
I don’t expect that fencing will be needed to protect the options for Campanula parryi — just some warning markers. Grazing deer families are not the issue. Campanula, whether white or blue, appear to be a “deer-resistant” genus — the deer pass them over while grazing; it’s probably genetic, part of their evolutionary fitness, although I dare not venture into that new labyrinth just yet. The greater threat comes from stray dogs and their two legged pursuers, all innocently trampling the back meadow.
In short, some vigilance will be required. But it will be worth it for evolution is at play.
A Postscript: On Science and Stories
I want to offer one final thought about how we might best marshal support for protecting bio-diversity.
As noted in the closing section of this essay, despite is legal merits, a species-based or science-driven approach to protecting bio-diversity is likely to be under-inclusive because it generally gives little weight to different forms, varieties or sub-species of an organism.
I also think that a purely taxonomic approach to protecting life’s natural wonders falls short for another important reason. It typically overlooks the role that “pre-scientific” approaches — whether religion, folklore or story-telling — have played in identifying, memorializing and conserving the world’s flora and fauna. This is hardly an original observation. Robin Wall Kimmerer, a botany professor at the State University of New York and a member of the Porawaromi Nation, wrote about this most eloquently in her 2013 book Braiding Sweetgrass.
A more recent book by Amitav Gosh, The Nutmeg’s Curse, argues that a plural view of nature is more urgent than ever. Gosh’s book probes the historic roots of the climate crisis. It argues that, since at least the 16th century, and then honed by colonial practice, our rampant use of the biosphere has been driven by a conception of the natural world — of all other species (including indigenous peoples ! ) — as mute and as no more than “brutes” having no consciousness or voice, and thus subject to unlimited exploitation or eradication.
To counter the ensuing environmental degradation, Gosh contends, it is essential to “imaginatively restor[e] agency and voice to nonhumans,“ so that humans become more engaged and empathetic. “[T]his is a task that is at once esthetic and political, he writes. “[A]nd because of the magnitude of the crisis that besets the planet, it is now freighted with the most pressing moral urgency.”
“What does it mean,” asks Gosh, “to live on Earth as though it were Gaia — — that is to say, a living, vital entity in which many kinds of beings tell stories? “ He continues: “For many contemporary nature lovers, the beauty of the forest lies in the wonders revealed by scientists; that is why ‘nature writing’ is often studded with the binomial names of the Linnean system.”
By contrast, says Gosh, in pre-colonial times, for many native peoples, “a name given by humans to a tree would not even begin to exhaust its presence,” because the tree and the forest itself also exist as part of a greater spiritual world that keep it alive and give it meaning. This is why storytelling, even myth making, “needs to be at the core of a global politics of vitality”, that is, of environmental restoration.
So perhaps I had it all wrong, starting with the learning from my treasured field guides. You may recall my earlier aside on the origin of Capanula’s colloquial name, harebells, from Kathryn Darrow’s book, Wild About Wildflowers. Darrow referred to the “old” (read, pre-modern) Scottish tale that witches (read, local herbalists) used the juice from these flowers to transform themselves into hares. Which led Scotland’s bluebells also to be known as harebells. An “esoteric aside” I said, and of no help to my taxonomic quest.
Had I got it backwards? Was the story I had once viewed as an “esoteric aside” in fact of central importance, and perhaps even more so than any binomial appellation later given to these winsome flowers. For at bottom, my taxonomic quest was driven by a desire to gain some recognition, some protection, and wonder for the unusual white form of this wildflower that chanced to bloom in our back meadow. Might not the harebell’s story — rich and magical as it is — do that even better than any new species name?
White harebells dancing in the breeze.
Once were herbalists with hands and feet like yours,
Gathering native blooms for the Solstice.
Now transformed by a potion, a scent.
Inhale it as they dance, if you dare.
Hence, when it comes to valuing nature, to giving it voice and protection, do we need more species or more vital stories? The answer is surely both. Indeed, perhaps the next generation of wildflower guides should make an effort to give both folk stories and taxonomy their due, all in the name of Gaia. Wouldn’t that make for a richer and more memorable read, while also opening the world of nature guides to a much wider audience.
I am not suggesting that we forsake the knowledge that evolutionary biology has brought to understanding the natural world. No, not for a moment. Taxonomy and evolutionary genetics have their place. It is just that science alone (the “name game”) may not be able to muster the power to preserve what it names. In the face of massive climate-driven extinctions, as Gosh suggests, we may also need a new vitalism — a vitalism that conjures as many new “nature stories” as we can craft and that revives the best from before.
Fantastic though they may be, these stories might imbue the biosphere with a new kind of empathetic character that connects more and more people to flora and fauna too long seen as mute and expendable. We know well by now that fictions are often more powerful that facts. Thus, if it is conservation we are after, in addition to the prestige (and protection) accorded species, might not the harebell’s magical story show us a parallel way forward.
A Further Postscript on White Forms of Campanula Parryi :
Since this essay was written, two other cases of white (or near-white ) petaled Campanula parryi have come to my attention.
One is a specimen collected in July 2017 near Salida, Colorado by Christina Alba that is part of the Denver Botanical Garden’s Kathryn Kalmbach Herbarium. Alba is an Assistant Research Scientist at the Garden. See this link.
Notably, the Garden’s Head Curator of Natural History Collections, Jennifer Ackerfield, whom I also consulted in preparing this essay, recently described two new species of high-alpine Colorado thistles (Cirsium funkia and Cirsium culebraensis). Her extensive taxonomic research on thistles is described here.
The other Campanula parryi sighting is a research quality observation of three white flowers sighted in August 2021 near Conifer Colorado and posted on iNaturalist at : https://www.inaturalist.org/observations/90960392
I would be grateful to any reader who can point me to other examples of this unusual form.