Stop and Smell the Irises: Does iris flower scent match their colors?
- Ivy
- Jun 17
- 7 min read
As we know, irises are named after the Greek goddess of the rainbow because they can be found in every color of a rainbow then beyond the rainbow with “black” (usually very dark purple) especially in bearded irises, with the first to hit market in 1938. This was a cross of blue and violet varieties with an iris called The Black Douglas made in 1934. There have since been developed many “black” varieties of iris, often with fun names like Storm King, Dark Boatman, and Licorice Stick. Yet, if European botanists had looked further, they would have found the endemic iris of Jordon in the Middle East that is quite naturally black in color, so named Iris nigricans (2).
Wonder if the black Licorice Stick iris smells like black licorice too?? It is in fact licorice scent from a dark purple iris that lead me down a fun olfactory path- what do all these colors smell like? Ever smelled the rainbow?? And do the scents match the colors? Because I’ve had a few hints/whiffs in that floral vein.
Irises are not just varied in their color, and scent, but in species as well with several of distinct flower structures and about a million varieties among the bearded irises. Irises all belong in the Iridaceae family of monocot clade and Asparagales order. There are officially 69 genera in the family and 310 species in the Iris genus. The main groups you will see in landscapes are bearded, Siberian, Dutch, reticulated (I. reticulata), flag* (I. pseudacorus) and similar wetland Japanese or “water” species (I. laevigata or more commonly I. ensata) though these are less *aggressive/invasive than I. pseudacorus yellow flag or even it’s cultivars. Just... don't plant flag irises. Really.
Irises are of course greatly extended beyond cultivated species like the many hybrids of bearded and Siberians. There are dozens of natural and wild growing native irises across the US, Europe & all over the Asian continent, with some variation in flower structures, roots, and of course color, but all being recognizable is “irisy” with the lower tepals and upward petals (falls and standards, in iris lingo) paired in threes with a few odd-ball exceptions.
And no, you can NOT go dig some up from a wild area to put in your garden, as most wild iris species do not survive transplanting. Look for a native nursery.
Back to sniffing these beauties!
What irises smell like is not easily answered, though a cursory look online tends to give a narrow definition of “iris scent”, typically from perfume-oriented writers. In truth, there are a LOT of scents that irises can have, but we’re also talking about 1 group- the Beardeds. This does include several species and some aromas are better known to certain species, but there is nearly as much olfactory variety as there are colors. The thing is- perfumers are usually not getting their “iris scent” from the flowers, but from their roots or rather rhizomes (swollen lateral semi-underground stems). All of it is toxic, fyi. Part of why I love irises- dangerous beauty, like a lady assassin of plants, except few people have actually died from an iris. Yet, some iris root is also used to flavor edible things, so it must lose toxicity in the long processing.
The perfume industry often calls the iris scent Orris and describes it as floral, powdery or even bread-like. But again, that’s usually from the roots. Flowers are also described- “complex and multi-layered, with notes of powdery, woody, floral, and earthy scents. It has a unique and intriguing aroma that is difficult to describe” (8). Yet sometimes you can also describe an iris flower with very familiar single scents. “What do irises smell like?” is like asking what apples smell like, or a home. There is a huge variety of scents and layers to them, so much to smell!
Some generalize iris as just sweet, or sweet and spicy with touch of vanilla and/or cinnamon, violet scented is also common. But some find the scents “hauntingly attractive” and thus the increasing popularity that iris scents are getting for perfumes and other scented things like candles or cosmetics. Even alcohols.
Quick smell of Chemistry:
There are primary scent chemicals of iris root (Orris) are a terpenoid irones group of chemicals and are described as spicy and rich. The flowers contain aromatic acetyl-ionone also used in perfumes which is sweet. The ironone family of chemicals is also found violets which is a common scent describer for iris flowers. One recent chemical analysis of 27 bearded iris flowers found over 200 chemical components extracted from the flowers. Terpenes, esters, and alcohols made up the majority of the flower aromas (12).
Croatian (I. croatica) & Dalmatic (aka I. pallida) irises are the best-known for fragrance and harvested for perfumes. Both are among the bearded iris group, also including I. germanica, and I. pumila. In contrast, the beardeds most bred for fancy colors are German and Hungarian cultivars. Dalmatic/Pallida commonly has that violet scent. But there’s a variegated variety that is famous for having a striking grape scent, like sweet grape candy of grape soda. The pale purple flowers contrast nicely the green & yellow striped leaf blades.
Sniffing Out Variety:
“There are too many fragrant irises out there”
-said sniffer Patric Mooney (3) apparently in a fit of insanity! “Too many”? Me thinks not. But I’m a bit iris-obsessed. Ir-ressed. Well, plant nerd.
It’s not just me. Even my beloved painter Claude Monet showed many irises with different varieties and species (Siberian, Germanic & even Dalmatic) in his paintings. Flags, stamps, coat of arms, and architecture accents even feature the iris shape, known as fleur-de-lis.
I recruited some friend* sniffers to describe irises they come across this past spring who do confirm there are grape or even grape soda scents and licorice. While other sniffers have found vanilla, and even chocolate scents. Less fun, some have been described as “wet dog”, carrot, or maybe more preferable- hawthorn flowers. And one facebook post declares a bearded iris that smells like root beer. And I must have one!
[Thank you Japrice & Chelsea for irises to sample and the Into the Woods Preschool for pointing out and sharing their black iris]
And it’s not just the flowers that smell interesting.
The rhizomes (underground swollen stems from which the blade leaves and roots emerge), most particularly of the I. pallida species, have a violet-like scented compound called Orris and the oil of these rhizomes is distilled for things like alcohol flavorings. But remember- all parts of irises are toxic when fresh, so apparently extracting from dried powdered rhizomes is alight for a few medicinal and flavoring uses, safer still is using iris scents for perfumes.
So what are the scents that we find in irises, other than sweet and violet or “powder” (like baby powder? Dunknow…)? And MY question- do the colors of irises tend to match their aroma as well, or is it random and I’ve noticed a small coincidence? Hypothesis- Yes iris colors and scents match up, meaning an orange or yellow iris will smell citrusy or a dark iris will smell deep like licorice or rum, and pale colors will smell faint or light like vanilla, baby powder, or fresh linen.
I got some help smelling from some local sniffers and found a lovely nursery site that actually had descriptions of their fragrant irises, not just “fragrant” or “sweet”. Collecting 33 such smelled specimens, here’s my data:
Irises with colors and scents, with last table of species lacking scents.
64% of sniffed irises scents matched their color profile
33% of sniffed irises scents did not match their color profile
6% (2) of irises didn’t have a clear match or mismatch. Is spicy musk an orange and purple smell? I couldn’t say so I left a couple as “?”.
Only the bearded irises had aromas. Dutch, Siberia, and flag species were just a pretty face with no depth. Can you tell beardeds are my favorite?
The horribly wetland-invasive and caustic yellow flag iris (Iris pseudacorus), very disappointingly found in a local nursery’s landscaping, unsurprisingly has no scent. See? No reason to have this plant, kill them ALL! They destroy wetlands!
Bearded irises are best known for their full rainbow of colors and lesser known for their fragrances, making it no wonder they are often so beloved in gardens. And they range from the common violet or sweet floral scents, to fruits, vanilla, spicey, chocolate, rootbeer, and even wet dog, which I luckily did not encounter. I have more to collect for my garden now. And I'll still keep the pretty Dutch irises that don't lend me any scent boost. Why don't some flowers have scent anyway? Well, it's an energy expense that some flowers don't need for attracting pollinators. Scent isn't just for our human noses that don't tend to pollinate many flowers. Unscented flowers are more for the birds (which can’t smell, nor taste spicy capsasin so they can eat hot pepper fruits).
The rainbow of iris colors and aromas is happily for any gardener to enjoy, and can even be enjoyed typically right before we celebrate Pride month in June as that's when many irises are wrapping up their blooming in temperate areas (in the northern hemisphere anyway).
So happy Iris Pride and happy sniffing and happy gardening to you all!
References:
1) https://wiki.irises.org/Hist/DevelopmentOfBlackIrises, & https://wiki.irises.org/Spec/SpecLaevigata
4) “champagne elegance” pic- https://www.gardenia.net/guide/delightfully-fragrant-bearded-irises
12) https://pubmed.ncbi.nlm.nih.gov/31067789/ Yuan, et al. Identification of Floral Scent Profiles in Bearded Irises, 2019
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