“Chrysanthemum parthenium, feverfew, was, as its name implies, cultivated as a herb for lowering the temperature, and its strongly aromatic foliage no doubt helped to sustain its image as a herb of considerable efficacy. Its white daisy flower and pale green chrysanth foliage can be detected on the fringes of many walled gardens. Its name is said to have been derived from an incident related in Plutarch’sLife of Pericles during which a man who fell while working on the Parthenon escaped death by grabbing hold of a clump of feverfew.”
“C. parthenium. Feverfew. This plant is generally accepted as a native, though some think that it was introduced by the Romans, on the ground that it is one of a number of trees and herbs whose Anglo-Saxon name is obviously derived from the Latin. In this case, feverfew is said to be a corruption of febrifuge, ‘taken from his force of driving awaie agues’ [according to John Gerard’sHerball.] But it is equally possible that the Romans found the plant already here, and merely brought its properties to notice.
A double variety was brought into gardens at the beginning of the seventeenth century, and was then regarded as ‘peculiar onely to our owne Countrey’. ‘It abounds in Britain’, wrote the Dutch florist Crispin de Pass, in 1614, ‘because it appears to be grown there with skill and industry, and indeed from thence many kinds of flowers composed of a manifold series of petals are first brought into the neighbouring countries.’
Later on, it became popular as a foliage-plant for bedding-out purposes, particularly the golden-leaved variety, C. parthenium aureum. As to its properties, it was held to be ‘a special remedy to helpe those that have taken Opium too liberally… In Italy some use to eat the single kinde among other greene herbes… but especially fried with eggs, and so it wholly loseth his strong and bitter taste.’ It was ‘very good for them that are giddie in the head, or which have the turning called Vertigo… also it is good for such as be melancholike, sad, pensive and without speech’.
It appears on garden lists in various spellings — ‘Double Featherfew’, ‘Double Feaverfew’, and ‘Febrefeu’ are among them — for nearly a handful of centuries…. It was called Parthenium by the early botanists because of a tradition (recounted by Plutarch) that it saved the life of a man who fell from a height — having presumably become ‘giddie in the head’ — during the building of the Parthenon….
The scent is supposed to be particularly distasteful to bees. Varieties of C. parthenium are sometimes listed as Matricarias.”
The fields are merely clods of darkest brown and here and there a bit of yellow-green, and little sparrows, silly, fresh, and daring, are darting over them like raucous children… And far away the city with its towers, with houses storming forth, so light and merry,
is like an image from a fairy tale. The air is quiet, filled with yearning, so that you wait for sky-blue larks and want to ride in slender rowboats.
Here stand white asters, white and pure, and there a head of cabbage, small and young. They’re like a long forgotten parasol in the middle of snow covered streets. A rabbit, running past, cannot believe it….
Alert readers (like you!) might notice that the two excerpts above — from books published in 1982 and 1971 — refer to the plant as Chrysanthemum parthenium, something that emphasizes what I wrote about in the first post: its current name Tanacetum parthenium is a recent enough change that even contemporary botanical references use the previous name. Those two excerpts also elaborate on the parthenium part of the plant’s name (which has remained constant) with rescue stories, though one might still puzzle about whether “grabbing hold of a clump of feverfew” would have mitigated against gravity.
From “Meaningful and Useful: A Plethora of Chrysanthemums” in Chrysanthemum (Botanical) by Twigs Way:
“[A plant] which has at times been awarded the ‘chrysanthemum’ title is the daisy-like feverfew. Easy to grow, it is native to Eurasia, originating in the Balkans, but long ago spread to northern Europe. Feverfew has a small, bright, daisy-like flower with white petals and a sunny yellow centre. It loves to grow in sunny places and spreads rapidly by seed to overwhelm flowerbeds on dry slopes. The feverfew was originally classified by herbalists of the seventeenth and eighteenth centuries as Chrysanthemum parthenium but later became Pyrethrum parthenium, before being finally (one hopes) transferred yet again to become Tanacetum parthenium, aligning itself with the tansy, which was also once a chrysanthemum.
“Originally given the common name ‘featherfew’ after its feathery leaves, the feverfew is widely regarded as most useful for fever, arthritis and headaches and is recorded as being used as an anti-inflammatory in the first century AD. It may well have been introduced into England from central Europe by the Romans, who used it for these medicinal properties…. In his 1597 The Herball; or, Generall Historie of PlantesJohn Gerard did not hazard a guess as to the feverfew’s familial or (in modern terminology) genetic associations, but instead listed its virtues in physic, including being a remedy for ‘those of a melancholic nature’ who might be ‘sad, pensive or without speech’….
“Feverfew has attracted renewed interest in its medicinal usage thanks to its parthenolide content, which preliminary research indicates may have an impact on cancer-cell growth. It was traditionally known as ‘bachelor’s buttons’, a naming it shared with cornflowers. Explanations for the derivations of this vary from the flower literally having the appearance of a button, to the wearing of a small posy of such flowers in the buttonhole to indicate romantic availability….
“The parthenium part of the plant’s name, which has remained constant, contains a reference to virginity, but this meaning (or the Latin name) is unlikely to have been known to the country folk who originated the name ‘bachelor’s buttons’ or the alternative ‘pale maids’.”
Acre on acre, mile on mile, Like spray from a waterfall, The little wild white asters Offer their beauty for all: Fairyland-flowers that frost Will copy on window panes; Blossoms, like breath of winter, Drifting the valleys and plains. When the wind passes they whisper, Like the sound of the sea in a shell, A silver good-bye to summer: Summer, farewell… farewell….
Hello!
This is the first of two posts with photographs of Tanacetum parthenium, that I took at Oakland Cemetery in October. This plant has a large number of common names (see here for an extensive list), but it seems that the most commonly used common names are Feverfew, Featherfew, and Bachelor’s Button.
As I’ve likely mentioned before, Oakland’s gardens include an extensive collection of plants from the Asteraceae family, a family that includes delights like aromatic asters, chrysanthemums, coneflowers, cosmos, daisies, goldenrod, sunflowers, tansies, and zinnias — among many others — which I’ve been photographing for about five years. In 2022, I started trying to identify the specimens I photographed more accurately and to segregate them by genus name, so that for at least the past three years, it would be possible to view those I identified as chrysanthemums and those I identified as asters, for example, independently. I’m sure I’ll continue to refine that as this body of work evolves, and perhaps at some point go back to older posts and give their tags a tuneup as I learn more.
The excerpt from Chrysanthemum (Botanical) by Twigs Way at the top of the post hints at the complexity that I sometimes encounter. The Tanacetum parthenium plants featured below not only have a large number of common names, but have also had shifting scientific names. At various times, they’ve been botanically known as Matricaria parthenium, Chrysanthemum parthenium, Pyrethrum parthenium, and now Tanacetum parthenium — the most recent genus name assigned after genetic analysis determined that the plants shouldn’t be classified as Matricaria or Chrysanthemum, and the genus Pyrethrum had fallen into disuse. The earlier names were often culturally reflective — Matricaria, for example, was derived from terms associated with maternal or reproductive health — but changed over time as horticultural observation suggested they had been categorized inappropriately, or scientific methods improved (especially in the 20th century) to refine their botanical characteristics and group similar plants more precisely. It will always be something of a moving target, I suppose, yet it’s weirdly fascinating to me how much I learn by just exploring how these names emerged and were modified over time.
This is especially true for the Asteraceae family of plants, which contains nearly 2000 individual genera, including the Chrysanthemum genus, the Aster genus, and the Tanacetum genus, which together include about 400 species, and are respectively referred to as mums, asters, and tansies. This might suggest something obvious: it’s difficult to identify specific species of many mums, asters, or tansies when working from photographs, because there are so many possibilities to choose from and those featuring similar color combinations — like the white-petaled, yellow-centered flowers in this post — create additional identification challenges. Even my favorite plant i.d. source, PlantNet, trips on the challenge sometimes, and will often simply identify plants like these as genus chrysanthemum or genus aster only, as it can’t differentiate among their subtle differences to figure out the species. Nevertheless I persist! — and hope that as I do more and more research, I’ll get better at targeting my photos with the right plant names. And I’ll keep doing it since I learn so much about plants, their history, and their botanical characteristics along the way — something that can only happen if I do the research.
When I use PlantNet as a starting point for identification, I upload photos one at a time so that it can analyze the plants from different perspectives, without one image influencing its analysis of another. With this series of photos, closeups like this one — while aesthetically pleasing — don’t provide PlantNet with enough information, since the plant’s stems aren’t visible and its leaves are out-of-focus in the background.
While PlantNet did identify it as Tanacetum parthenium, the likelihood of a match was around half a percent — a low probability that in itself reflects the fact that so many Asteraceae family flowers look very similar. With this image, instead…
… PlantNet had more detail to work with, and the probability that the plant was Tanacetum parthenium increased quite a bit. Yet it was still quite low — so I was left with only a slim possibility that the identification was correct, but could conclude that the plant’s leaves were key to getting its name right. As historical botanical drawings have played a role in plant identification for several centuries, I searched for botanical drawings of the plant by its long-established common name “feverfew” to see how naturalists have documented the plant in the past. Click here if you would like to see the search results, where the plants’ leaves — and their distinct parsley-like appearance — are very evident, helping to confirm that Tanacetum parthenium was the correct botanical name for this plant.
“Evolution teaches us that thistles, daisies, sunflowers, asters, and all the triumphant horde of Composites were once very different flowers from what we see today. Through ages of natural selection of the fittest among their ancestral types, having finally arrived at the most successful adaptation of their various parts to their surroundings in the whole floral kingdom, they are now overrunning the earth.
“Doubtless the aster’s remote ancestors were simple green leaves around the vital organs, and depended upon the wind… to transfer their pollen. Then some rudimentary flower changed its outer row of stamens into petals, which gradually took on color to attract insects and insure a more economical method of transfer….
“As flowers and insects developed side by side, and there came to be a better and better understanding between them of each other’s requirements, mutual adaptation followed. The flower that offered the best advertisement, as the Composites do, by its showy rays; that secreted nectar in tubular flowers where no useless insect could pilfer it; that fastened its stamens to the inside wall of the tube where they must dust with pollen the underside of every insect, unwittingly cross-fertilizing the blossom as he crawled over it; that massed a great number of these tubular florets together where insects might readily discover them and feast with the least possible loss of time — this flower became the winner in life’s race. Small wonder that our June fields are white with daisies and the autumn landscape is glorified with goldenrod and asters….
“[The} Late Purple Aster, so-called, or Purple Daisy… begins to display its purplish-blue, daisy-like flower-heads early in August, and farther north may be found in dry, exposed places only until October. Rarely the solitary flowers, that are an inch across or more, are a deep, rich violet. The twenty to thirty rays which surround the disk, curling inward to dry, expose the vase-shaped, green, shingled cups that terminate each little branch….”
This year the autumn is a restless sea Of weaving crests of waving goldenrod And swirling billows of the purple aster Whose foaming mauve tinges the tumbling air; Across the hills and hollows of that ocean A fleet of trees rides, with slow yellow sails And crimson pennons ribboning the wind, Toward the harbour of the horizon’s bar Where an invincible navy waits at anchor, A fleet of clouds, unfurling sails of snow.
These flowers are among the first asters to bloom across Oakland’s autumn landscape, typically appearing in September then expanding and tumbling throughout their surroundings over subsequent weeks. Their blooming time coincides with a similarly sized white aster — probably Tanacetum parthenium or a close relative — whose photographs I’ll feature in the next two posts after this one. The simultaneous appearance of these two variants, one with purple flowers and one with white flowers, is one of the first signs that we’re moving from later summer to early fall, their abundance marking that seasonal change just like the appearance of daffodils and early irises usher in spring. We might think of them as transitional plants, as they bloom and then are gone before even later blooming mums and asters take over the gardens as the oak and maple tree leaves start changing colors.
For this post, I wanted to show how these Aromatic Asters are used in memorial displays like those at Oakland. Their mix of wild, native, and naturalized variants makes them especially appropriate historically: asters of various kinds — especially those that bloom late in the year — fill in the spaces where earlier flowers have receded and have been used for that purpose for centuries. Aromatic (or similar) Asters that produce a large mass of purple flowers connected by stems that twist and turn in all directions create a muted yet colorful contrast as they mound upward then bend forward in waves. In Victorian, memorial, and cultural symbolism, the color purple is often used to convey dignity, respect, and remembrance, and lighter shades like those of Aromatic Asters encompass those meanings while creating a serene contemplative space.
If you look closely at some of the photos where I’ve zoomed in on the blossoms, you may also be able to see how that purple/violet color gets reflected in the memorial stones and gravel nearby. This reflected visual effect — one that is apparent even on overcast days — is intense enough that it comes through in photographs and is equally compelling when observed in person: studying the scene gives you a sense that you’re enveloped in the color purple, regardless of where you stand, and with all its symbolic meanings. The positioning of these asters — that is, where Oakland’s landscapers chose to plant them — is likely intentional, as none of the growth intrudes upon the memorial markers but instead complements them in terms of both color and texture. These visual effects are even more remarkable, it seems, since each individual flower is less than an inch in diameter, yet their combined density creates a purple tide that can be seen from every vantage point.
“Asters, someone once said, ‘are stars fetched from the night skies and planted on the fields of day.’ Indeed, it often seems as if there are as many asters as stars when September and October roll around. And to those who have studied the subject a little, it seems almost as if there are as many aster species — and, lately, aster genera — as there are asters…. Aster, of course, means ‘star,’ as in astronomy and astronaut, descriptive of the star-like form of the flowers….
“Until the 1990s, more than 150 North American plants were included under the genus Aster. However, close study, using DNA testing and other techniques, has determined that our ‘asters’ are not quite the same as Old World asters. Almost all North American plants once classified under the genus Aster now bear such tongue-twisting generic names as Symphyotrichum, Oclemena, Chlorolepis, Eurybia, and Doellingeria….
“Since there are so many species, aster spotting is almost an autumnal sub-hobby of wildflower hunting. With so many varieties-some exceedingly rare-amateur flower sleuths could spend many hours not only in finding but then in identifying asters.
“This is sometimes no simple task, for most wildflower guides do not pretend to list every species you might come across. Even armed with an extensive catalogue, identification can be tedious and technical, requiring close inspection of the leaves, seeds, or other parts. In addition, asters in the wild tend to form hybrids and to create tiny races that sometimes become distinct enough to be classified by some botanists as species….
“You don’t need a botany degree, though, to identify most of the common asters. Actually, it’s fun and challenging and, in the process of trying to separate similar species, you can learn a good deal about plant identification and structure.
“The season for aster hunting starts in August when the white wood asters (Eurybia divaricata) and other early species appear. September is the best time, since virtually every variety is in bloom sometime during the month. The flowers are a prelude to autumn’s bright colors…. Blues, purples, and variations thereof are common colors among asters. Many white varieties are also common, though often the white species will produce blossoms with subtle pastel tints of violet, pink, or blue. In many species the center disks start out yellow but turn to purple or brown later on.”
Referring to some asters as daisies is pretty common, as many asters look a lot like the daisies we accurately call daisies; and the family name — Asteraceae — is itself often called the Daisy family. But the historical nomenclature can be even more confusing than that, as the family was once called Compositae or the Composite family, because most of its extended family’s flowers are composite flowers. The quotation at the top of this post elaborates on that even further, explaining how some of the Aster family members were moved into their own genera — Symphyotrichum, Oclemena, Chlorolepis, Eurybia, and Doellingeria, and how that was a fairly recent development arising from genetic testing that occurred as recently as the 1990s. It is perhaps (or perhaps not!) interesting how these complex names of plants get modified in conjunction with scientific advances, but the common names — often derived from cultural associations, observed growth patterns, or their appearances — have a sticktoitiveness that their official names do not.
Composite flowers, as we have learned, can simply be thought of as flowers growing out of flowers — sometimes on top of and other times surrounding each other — such as the yellow and orange toppers we saw on the Zinnias I posted previously. Zinnias show off one of the most obvious visual occurrences of the composite flower feature, whereas these Painted Daisies and Aromatic Asters are a little more subtle about it. I was very pleased, however, to discover the early nineteenth-century poem “Asters and Golden Rod” by Helen Hunt Jackson, which describes a regal display of goldenrod standing guard over a patch of purple asters and takes note of their disk florets. The poem also reflects how the striking autumn color contrast between goldenrod and asters can be found in purple asters themselves…
… and evocatively describes an often overlooked variation in the appearance of asters that becomes apparent when we photograph them close up. At any given moment of image capture, the “little earths” of some disk florets have dispersed their seeds into the wind (turning the floret brown), while others haven’t gotten around to it yet, so those disks are still bright yellow and orange:
With every autumn’s blaze of Golden Rod, And purple Asters everywhere will nod And bend and wave and flit;
Until, like ripened seed, This little earth itself, some noon, shall float Off into space, a tiny shining mote, Which none but God will heed….
“Although introduced as late as 1796, zinnias (Zinnia elegans) seem always to have carried the reputation of ‘old maid of the garden.’ During the first half of the nineteenth century, this coarse flower with plain scarlet and crimson blossoms persisted reluctantly in the trade….
“With the advent of double types in the late 1850s, enthusiasm for its possibilities increased. Charles Hovey observed in 1864 that, although still improving ‘under the hands of skilled cultivators… there is no reason to suppose it will not in time give us as great a variety as the dahlia.’
“Dwarf, double forms did arise to enter the ranks of bedding-out plants, but their ungainly or unattractive habit and unreliable colors from seed rendered their value questionable in highly controlled situations. Giant or mammoth strains entered the trade by the late 1880s, allowing the zinnia’s ungainly character full expression….
“This branching, freely growing flower delighted the creators of the ‘old-fashioned border’ during the early twentieth century. But as late as 1929 we are reminded of the zinnia’s earlier reputation. As [Harold] Hume observed, ‘Today it has grown forth into the prize and pride of many a garden… gorgeous and self-assured, new formed, new faced, new named, its despised position of former years entirely forgotten.'”
I thought I could not bear to see the zinnias go — color of fire they were against the garden’s green: brick red and crimson, scarlet, gold and flame, fawn and maroon, cerise and coralline.
Frost came one night, finis in its track: flowers turned to cinders, foliage went black.
There were no zinnias left to crown the gardens year, but on the lofty maple towering overhead leaves were burning skyward, wind-driven flames, copper and saffron, cinnabar and red.
I think my photos cover most of the colors in the Elizabeth Yates poem above — especially since some of those colors are shades of the others — so we can pretend I matched the photos to the poem. I gathered all the double-flowering Zinnias together for this post, not realizing their significance until I started assembling them and conducting some research on this particular Zinnia form.
I first photographed Oakland’s Zinnias in 2021, and at the time didn’t know what they were (and hadn’t yet discovered PlantNet for plant identification), so simply called them wildflowers (see Ten Wildflowers and Three Butterflies) — because they resembled those motley collections of flowers that you might find at the edges of a forest or see on the side of a road. I didn’t photograph them again until 2023 and 2024, when they had incrementally spread across their hill and homeland, increasing their overall presence in the landscape each subsequent year.
While learning more about Zinnias for this post, I looked through all the previous years’ photos and saw that I didn’t have any showing the double form. This introduced a potential mystery: either I just hadn’t photographed any double Zinnias in 2023 or 2024; or, there weren’t any. Given that each of my earlier photoshoots followed the same pattern as this year’s trip — two visits in late summer and early fall — it seemed unlikely that I would have passed over them, especially given how much time I spend dwelling over any batch of flowers to capture their colors and shapes. So it’s more likely that they weren’t there, and that either Oakland’s gardeners planted them in 2025, or some of the single Zinnias developed the double form this year. To speculate on and potentially resolve this part of the mystery, let’s turn to the landscape itself and observe the messages it might be sending us.
Here we have two photos of double Zinnias from the galleries below. In the first photo, we see a double Zinnia growing in front of some Iris leaves, between — shall we say — a rock and a hard place, in a crevice barely six inches wide. In the second photo, we see one double Zinnia growing among a half-dozen single Zinnias. Neither of these placements suggests intentional planting: capable gardeners are unlikely to try growing one Zinnia in a crevice, nor plant one double among a group of singles. Instead, both growth patterns reflect the randomness typical of plants that are propagating on their own, where fertilized seeds have been distributed by pollinators or the wind, and favorable conditions let them sprout, take root, grow, and bloom from one season to the next.
For this speculation to be true, it would have to be possible for double Zinnias to evolve from single Zinnias. To help me understand whether or not that was possible, I turned to my digital research assistant, Claude.AI, and asked some questions about how a generational transformation between single and double Zinnias might take place. Here’s part of the explanation, where “ray florets” refers to each row of flower petals a Zinnia typically produces, and “disk florets” refers to the tiny composite flowers that grow at the top of a Zinnia’s pear-shaped seed structure.
This transformation doesn’t happen randomly — it’s the result of mutations in specific developmental control genes that regulate how the flower forms as it develops. To understand this, you need to know a bit about how composite flowers like zinnias are built at the genetic level.
During flower development, the plant must make a series of decisions about what kind of structures to produce and in what order. In a normal single-flowered zinnia, the genetic program says something like: “First, produce one whorl of ray florets around the perimeter. Then, switch modes and fill the center with disk florets.” This creates that classic daisy appearance — showy outer ring, functional inner disk.
The mutations that create double-flowered forms disrupt this tidy program in one of several possible ways. Some mutations affect genes that control the transition from “make ray florets” to “make disk florets.” When these genes malfunction, the plant essentially forgets to make the switch, or makes it much later than it should. The result is that the flower keeps producing row after row of ray florets instead of transitioning to disk florets. This is why heavily doubled zinnias have so many petal layers — the developmental program that should have said “stop making rays, start making disks” failed to activate properly or activated much later.
The production of “row after row” of flower petals is exactly what we see in fully-formed double Zinnias like those in my galleries below. Claude also went on to describe the genetics by which this transformation might occur in some detail — a couple of thousand words of detail, actually — and explained that, due to cross-breeding by humans or nature, any given Zinnia might contain the potential to produce flowers in the double form, and this potential might partially express itself between generations.
This seems to be confirmed by my Zinnia photographs from previous years: here we have some examples of that doubling potential emerging over time, where two of my photos from 2023 and two from 2024 show the flowers starting to develop a second row of ray florets. These aren’t just overlapping petals from a single row, but petals that are clearly growing from a slightly higher point at the center of the flower, and on top of the first row. That horizontal or height difference is most evident in the first photo; though once you see it, it’s easy to identify in the other three photos as well.
You never step in the same garden twice, of course, and I don’t know which of these Zinnias are perennials and which ones are prolifically-seeding annuals — so it’s not possible to know if I’m observing the same plants taking on different forms, or new variants expressing their double potential. In either case, however, next year’s crop will likely include even more double-flowering Zinnias, and, if it does, that will be strong evidence that the plants are producing additional forms on their own as each generation reappears.
“Zinnia was named in honor of John Godfrey Zinn, a German botanist who flourished in 1757, when the science was in its infancy. In the cultivated plant of today can hardly be recognized the primitive flower found in the fields and roadsides of the Southern States, which, even in its simplest form, has been considered handsome. Formerly the blossom was only scarlet, and single; but care in propagation has doubled it to the center, and it has sported into hues many, rich and varied….
“The flower perishes slowly without closing its petals, losing its bright tints and assuming more sobriety as its days are numbered. On this account it is sometimes called Youth and Old Age.”
Between form and force of color to find the illuminating place of order where fruit trees soar no longer bare and brandish oranges, figs, mangos above Birds of Paradise sailing in place, orange flower-ships of natural grace, gladiolas pointing bluntly through green blades above red zinnias buttoning up their patch until luscious fruits and flowers are too much and the fertile garden shrivels, picked, dead, dazed in silent time of sun and stone, waiting dumbly for the sacred time of rain when nature and man kindle care into color-bursts again, and rejoicing air crystallizes with bright, dying revelations to teach our eyes wonder, art of glory.
Hello!
This is the second of three posts with photographs of Zinnias from Oakland Cemetery that I took in August and in October; the first post is Dazzling Autumn Zinnias (1 of 3). Here we have another collection of single-flowered Zinnias (those that have but one row of flower petals beneath their pear-shaped seed structure and tiny composite flowers), in variations of red and magenta colors ranging from pure red to blends of red and magenta.
Let’s explore these color variations, since they have more significance than just looking good in photographs. As we’re very fond here of traveling back and forth between the nineteenth and twenty-first centuries — we’ll start with this chart showing the separation of light from the sun into the colors we can see, from page 95 of the 1856 book Chemical Atlas; or, The Chemistry of Familiar Objects by Edward Livingston Youmans.
For his chapter entitled “Chemistry of Solar Light — Solar Dynamics,” Youmans conducted numerous experiments to analyze the color and heat-producing qualities of sunlight. Here’s an excerpt from that chapter where the author introduces several concepts that we’re going to connect — believe it or not — to the color variations in these Zinnia flowers while we speculate on what those colors tell us about how pollinators like bees might interact with the Zinnias. Youmans writes:
“The radiations which flow from the sun to the earth are capable of giving origin to several different kinds of effect. One of its effects is produced upon the animal eye, and is called light. In what manner light, or the luminous force acts upon the eye to generate vision, or cause the animal to see, we do not understand. We know many of the laws of light, but how the visual organ is finally affected in producing the sensation of vision, is not comprehended….
“If a ray of light be admitted through a small aperture into a dark room, and be suffered to fall upon a triangular prism of glass, it will not pass through it, and go forward in a straight direction across the room; but it will be turned out of its pathway (refracted), and be thrown upon the opposite wall, not in the form in which it entered the room, as simple white light, but decomposed into an oblong image of the most brilliant colors, which is called the solar spectrum….
“The colors produced under these circumstances are supposed to be the components or constituents of white light…. When the image or spectrum is thus formed, the colors are not seen with a clear and sharp outline; they blend and melt into each other, so that it is difficult to fix the line at which one ceases and another begins….”
If you look at more modern renditions of the color distribution Youmans provides here, you’ll see that one of his key insights — that the colors “blend and melt into each other” — is equally apparent in graphics like this one, where you cannot detect clear boundaries between individual colors. This is true even when the graphics, like Youmans’ image, identify the colors red, orange, yellow, green, cyan, blue, and violet explicitly. These distinctions are only approximate, are always better expressed as color ranges — like the gradual transition from red to orange — and show why the number of colors we actually can see is often considered to be in the hundreds, thousands, or millions, depending on the context. That same graphic also leads us to those qualities of light that aren’t apparent to humans: infrared (beyond red and capable of producing heat that some pollinators can detect) and ultraviolet (beyond blue and violet), both of which are perceivable by or visible to pollinators whose senses can react to color properties we find inaccessible.
The blended range of colors presented by any of these individual Zinnia flowers is very evident in photos like this one…
… where the foreground flower shows a mix of red and magenta on its petals, and Lightroom doesn’t detect any colors other than red or magenta on those petals. Our vision doesn’t identify distinct boundaries between the two colors, but we’re certainly aware that both are present even though they’re inseparable. If, however, we take the same image and convert it to black and white, then increase magenta saturation while reducing red saturation, we learn from that variation how much magenta is actually present in the flower petals and that it — rendered as white in this image — is more dominant than red.
Now, let’s pretend we’re bees. As bees, we don’t see the color red; we’re drawn to colors close to or in the ultraviolet range — those from blue-violet and beyond in Youmans’ illustration — including colors that humans don’t see. So while humans see the flower in its color version, bees will see it more like our black and white version because magenta — a color chemically constituted with equal parts red and blue — contains enough blue to push the color toward the blue-to-ultraviolet range.
While this doesn’t mean the bee sees this Zinnia as a color-inverted black-and-white photograph, it does imply that the presence of magenta and its blue components creates color or contrasting patterns that are visible to that bee. Here’s an explanation of how that might work, from the book What the Bees See by Craig P. Burrows:
“If you think about all the colours of the rainbow and beyond on both ends of the light spectrum, humans see from the reds up to the blues. Bees don’t see the reds, but they do see past the blues into the ultraviolet spectrum. The contrasting colour patterns that matter to bees are different [from] the contrasting colour patterns that matter to humans. Using [ultraviolet] fluorescence photography… helps us to see some of the patterns on flowers that are visible to bees but invisible to us. Ultimately the benefit of seeing UV to an insect like a bee is to enable perception of contrast — of the flower from the leaves, and in the flower itself. Those striking patterns help the insect to identify pollen and nectar.”
By converting this image to black and white while selectively adjusting red and magenta saturation levels, we can simulate the effect of the ultraviolet photography Burrows describes — not to reproduce its capabilities exactly but simply to show how the presence of magenta might reveal hidden patterns in how these colors are distributed across the petals. In our black and white version, the bright white areas show where magenta — with its blue-violet component that bees can perceive — is most concentrated, particularly along the petal edges and tips. The darker areas represent zones where pure red dominates, color wavelengths that would appear dim or dark to bee vision. This technique isn’t showing exactly what a bee sees, but it does reveal contrast patterns that our human eyes naturally blend together into a uniform arrangement of magenta and red. To us, these blended colors are aesthetically pleasing; to bees, the resulting patterns likely create “visual guides” that direct bees from the petal edges inward toward the nectar-rich center.
The concentration of bee-visible patterns at the petal edges suggests these flowers have evolved sophisticated optical characteristics that remain appealing to pollinators whose vision differs dramatically from our own. These highly visible color patterns, along with the Zinnia’s relatively long blooming period and the way it produces easily accessible flower structures atop three- or four-foot tall stems, explain why groups of these zinnias attract so many different kinds of pollinators for several weeks toward the end of every summer and well into the fall.
