From “Yellow” in A Guide to Bearded Irises: Cultivating the Rainbow for Beginners and Enthusiasts by Kelly Norris:
“I think we take yellow for granted in the iris world, despite the fact that clarifying it from sodden and sullied to lustrous and sparkling was one of the greatest challenges of iris breeding in the 20th century. Many have credited the venerable ‘W. R. Dykes’ (Dykes-Orpington 1926), the iris named for the godfather of the genus, with starting it all — stirring frenzy on both sides of the Atlantic for sun-kissed tints on iris flowers.
“The range of yellow could cover continents in geographical terms. From the palest butter and white blend like that of ‘Melted Butter’ (Fan 1994) to the eye-searing, dark cadmium yellow blossoms of ‘Throb’ (Weiler 1991), yellow unspecifically describes many colors.
“But for much of the iris’s existence, yellow was a rare color, save the few golden or dirty yellow examples of Iris variegata or I. pumila. The earliest yellow, and at that a pale naphthalene yellow, was probably ‘Flavescens’ (De Candolle 1813), an old-fashioned diploid still found along highways and around old homesteads. It seems that generations of gardeners have passed this variety around, or it’s seeded with vengeance beyond the confines of its planting space. Either way, it’s still a simple charmer worth having in stock should an ugly fence or shed need some herbaceous company.
“But early diploids like ‘Flavescens’ were limited in their ability to transcend their own murkiness and fulfill a breeder’s quest for shiny, lustrous yellow. The conversion of diploids to tetraploids made this jump effortless. The originator of the most important yellow of the 20th century, W. R. Dykes, earned the honor of having a clear yellow tetraploid seedling of his named posthumously after him. Though the parentage remains unknown and subject to speculation, there’s no arguing that almost every yellow tall bearded iris and many median irises trace back definitively to ‘W. R. Dykes’.”
From “Irises” in Black Ash, Orange Fire: Collected Poems 1959-1985 by William Witherup:
Opened the kitchen curtain
for light
and was shaken awake
by your purple and yellow irises —
swollen and dripping color
on the morning canvas.
Iris, messenger from the gods
and goddess of the rainbow.
Beauty, dressed in her classic
and romantic robes,
or just pure flower, nameless….
This morning I pulled
the curtain on your garden
and a rainbow
arced into my coffee cup.
Hello!
This is the ninth of ten posts featuring photographs of irises that I took at Oakland Cemetery toward the end of April. The previous posts are:
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (1 of 10);
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (2 of 10);
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (3 of 10):
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (4 of 10);
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (5 of 10);
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (6 of 10);
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (7 of 10);
Nature’s Palette: Exploring Iris Colors, Their Culture, and Their History (8 of 10).
It seems we took a little break after the eighth post in this series! It wasn’t really a planned break, but starting in the last week of June, we had the longest stretch of rain- and thunderstorm-free days that we’ve seen all spring. After April, May, and most of June made me feel like I’d put down roots in a rainforest, I finally got some consecutive dry days to work in my yard, clean up storm debris, discard plants that drowned in their pots, pull up weeds, and add a few plants for 2025 — including a couple of new daylilies (one called Cosmopolitan and one called Beyond Riches); two different kinds of canna lilies (one called Red Golden Flame and a pair called Bronze Scarlet); and some dark red Dipladenia, the shrubby cousin of the Mandevilla vine. Since my planting season got off to such a late start, I chose plants I know are good at handling the July through September Georgia heat. I’m sure I’ll photograph them all as they take root and start blooming, probably later this month or in early August. But for now, let’s get back to our Iridaceae….
The irises in this post and the next one will include several variations that show off many shades of yellow. As Kelly Norris suggests in the quotation at the top of this post, we may think of yellow irises as very common, perhaps ranking next to purple as one of the most common iris colors. Yet as we’ll explore in these last two posts: the yellow irises we see today have a complex natural and genetic history, where they’ve evolved from the pale yellows of their wild ancestors or early garden inhabitants to the richly colored and textured irises produced by modern breeders.
In one of my previous posts, I introduced a botanical drawing by 17th-century German artist Hans Simon Holtzbecker, who also created this drawing showing a purple and yellow pair side-by-side:
That Holtzbecker chose to pair these colors could be coincidental, or it could reflect his observation of purple and yellow irises found together in the European gardens he studied for his drawings. The right side of the drawing captures his interpretation of yellow shades that would have been prevalent among irises 400 years ago, showing the pale, dirty, or slightly golden tones Norris describes at the top of this post. Botanical drawings like this served a function that would later be provided by photography: documenting the forms and colors in the natural world, where artists like Holtzbecker produced accurate representations of the shapes and shades of specimens they studied.
When you look at Holtzbecker’s drawing, you’ll see where elements of the yellow iris that would receive less light — the throat of the flower, the bases of individual petals, or where the petals are curved — appear darker as the colors seem to shift from yellow toward orange. This is also true among my photographs, like this one…
… where Lightroom detects orange only in the flower’s beards, or in the most shaded sections behind each beard toward the center of the flower. The rest of the flower reads as yellow, whose tones we interpret differently based on the amount of light reflected by the petals. Had I photographed this flower in full sunlight, those subtle yellow tonal variations would not have been as evident. Light filtered through clouds not only reduces the amount of yellow coming from the sun itself, but also lets us see more of the color variations present in the flower. And yet: even filtered through the clouds, the saturated yellow in these irises was substantial enough to splash a yellow color cast across the entire image that was, thankfully, easy to correct by adjusting white balance.
I split my photographs of yellow irises between this post and the next one based on their location in the gardens. This post shows newer plantings that normally get full sun; the next one will include yellow irises from older sections where they receive partial sunlight at the edges of plantings like shrubs and trees, and are positioned among memorial structures placed in the cemetery decades ago. These location differences will help us see how environmental conditions affect an iris’s color, and connect us to the botanical history of and the chemistry behind an iris’s production of color.
The color consistency in these irises places them in the color category called “self irises” — where all the petals of both the standards and falls show one solid color. That consistency is evident even in the partially opened flowers (as shown in the first twelve gallery images below), and is different from the buds of irises like Iris pallida ‘variegata’ where — as I show in my fourth post in this series — the emerging flowers present the color variations they’ll contain at maturity. The intensity and saturation of yellow in these irises, however, tells us a lot about how they might have evolved from their paler ancestors.
The appearance of yellow in these irises is determined by their carotenoid production, the term “carotenoid” referring to the yellow, orange, and red pigments present in biological entities including flowers, fruits and vegetables, and happy creatures like canaries and flamingos. For our irises, though, carotenoids (think of the color of carrots as an easy memory trick) serve more than one purpose: they produce the yellow colors we find so appealing, they help the plant absorb sunlight for photosynthesis, and they protect the flower and the plant from getting sunburned by that same light.
Imagine, for a moment, that you spent your days standing in a rectangular garden at Oakland Cemetery, where you faced the sun all day long and had no access to any shade. You’d need epic amounts of sunscreen to keep from getting burnt to a crisp — something these yellow irises face during their entire blooming season. The irises, however, have their own coping mechanism: the intensity of the sunlight across their dense, compact cellular structure encourages them to produce more and more carotenoids in response, each increase in carotenoids providing an additional layer of protection while simultaneously ratcheting up the level of saturated yellow color we see in the blooming flowers.
The ability of our irises to do that is not accidental, and it’s unlikely that yellow irises like those Holtzbecker illustrated would have been able to survive or even tolerate intense, all-day sunlight. Irises of such saturated and protective yellow are distinctly modern: their development occurred in the twentieth century, enabled (as Norris states above) by “the conversion of diploids to tetraploids” — a chemically complex discovery through which geneticists doubled the amount of genetic material available in developing irises, enabling the creation of irises with greater color saturation and vigor. Newer cultivars like Throb from the early 1990s — an iris that’s very close in color saturation, appearance, and form to those I photographed — clearly demonstrate the results of these revolutionary efforts (originated by William Rickatson Dykes) to produce irises that were even more sun-tolerant than their predecessors.
Thanks for reading and taking a look!
