From “Zinnia” in The Floral Kingdom, Its History, Sentiment and Poetry (1876), edited by Cordelia Harris Turner:
“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.”
From “The Essence of a Garden” in Ambiguous Dancers of Fame: Collected Poems, 1945-1985 by James Schevill:
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.
Thanks for reading and taking a look!
