Is purple a natural rose color?
Roses come in a wide variety of colors, from the classic red rose to white, pink, yellow, and even blue or black roses. But one color that gives many people pause is purple. Purple roses look striking and exotic, but is purple a naturally occurring rose color? Or is it achieved through breeding and genetic modifications?
In this article, we’ll explore the history of purple roses, look at the science behind rose colors, and examine whether true purple roses exist in nature. We’ll also overview the most common ways purple color is introduced into roses today. By the end of this article, you’ll understand the difference between natural and hybrid purple roses.
The History of Blue and Purple Roses
Roses have been cultivated by humans for thousands of years. And for most of history, blue or purple roses have been the stuff of legends. Ancient societies treasured stories of blue and purple roses as symbols of mystery and unattainable beauty.
In many cultures, blue or purple roses were believed to have mystical properties. They were associated with royalty and spiritual enlightenment. The rarity of seeing a blue or purple rose in nature led to their mythical status.
It wasn’t until the 19th century that horticulturalists started to make serious attempts at hybridizing truly blue and purple roses through selective breeding. Hybridizers discovered that delphinidins, the pigment molecule responsible for blue/purple shades in flowers, is notoriously difficult to produce in roses.
Getting blue pigmentation into roses proved an immense challenge. But hybridizers were driven by the dream of creating an elusive blue rose.
The Genetics and Biochemistry Behind Blue/Purple Roses
To understand why blue and purple roses were so difficult to achieve, it helps to look at the key factors that influence rose color:
Pigment molecules – The specific types and concentrations of pigment molecules in rose petals determine color. Key pigments are anthocyanins (red, purple, blue hues) and carotenoids (yellow, orange hues).
pH – The pH level of cell vacuoles in rose petals impacts how pigments are expressed. More acidic conditions shift color toward blue/purple, while alkaline conditions shift toward red.
Co-pigments – Other organic compounds in rose petals, like flavonoids and metals, can form complexes with anthocyanins. This stabilizes and intensifies blue/purple hues.
Delphinidins – These are anthocyanin pigment molecules that provide blue/purple coloration. Roses naturally produce cyanidins for red/pink hues but lack the ability to synthesize delphinidins.
Let’s explore these factors in more detail:
| Factor | Role in Rose Color |
|---|---|
| Pigment molecules | Anthocyanins provide red, purple, blue hues. Carotenoids provide yellow, orange hues. Total concentrations and ratios determine final color. |
| pH | Low pH shifts anthocyanins toward blue/purple. High pH shifts toward red hues. |
| Co-pigments | Flavonoids & metals stabilize/intensify blue anthocyanin pigments. |
| Delphinidins | Provide blue/purple hue. Roses lack ability to synthesize delphinidins. |
As you can see from this overview, several biochemical factors need to align to achieve blue or purple roses. While roses produce plenty of red and pink pigments, they don’t naturally generate the blue/purple anthocyanins.
Through selective breeding over decades, hybridizers coaxed roses to produce more co-pigments and altered petal cell pH to favor purplish hues. But the final hurdle remained introducing delphinidins into roses.
Early Hybridization Results in Lavender and Mauve Roses
It wasn’t until the 19th and 20th centuries that rose hybridizers had the scientific knowledge to start manipulating rose biochemistry and genetics to breed for purple hues.
Using conventional breeding, they identified and selected roses with the most co-pigments and acidic petal cell conditions. This allowed them to gradually enhance production of purple-ish anthocyanins from the pigments roses already contained.
The first results were roses with novel mauve and lavender shades. While beautiful, they remained far from a truly purple rose with intense blue-purple pigmentation.
| Year | Milestone |
|---|---|
| 1840s | First mauve roses bred by crossing Rosa centifolia and Rosa gallica varieties. |
| 1910s | Lavender roses with more purple tones bred by Robert B. Pyle. |
| 1920s-30s | Pyle and Wilhelm Kordes continue work hybridizing lavender roses with increasing purple hues. |
While not completely purple, these successes showed it was possible to significantly alter rose color through crossbreeding and laid the groundwork for further advances.
Introducing Blue Pigments Through Genetic Modification
By the late 20th century, advanced genetic engineering techniques like transgenic modification emerged. This allowed scientists to open up new possibilities by introducing genes from other flower species.
In 2004, Japanese biotech company Suntory succeeded in creating the Applause blue rose. This was the first truly blue rose, achieved not through conventional breeding but by transplanting a gene from pansies that encodes for delphinidin production.
Additional genetically engineered blue/purple rose varieties have followed from Suntory and other companies. These roses get their intense blue-purple pigmentation directly from delphinidins produced via the inserted gene.
Examples include Suntory’s Blue Moon roses, with blooms an iridescent blue-purple, and more recently their Moon Violet roses in deep purple shades. Other genetically modified purple roses like AVALANCHE+ Purple breeding lines also rely on delphinidin production.
Natural Purple Roses – Do They Exist?
We’ve explored how hybridizers first bred lavender and mauve roses through selective breeding, then used genetic engineering to create truly purple flowers by inducing delphinidin synthesis.
But what about naturally purple roses without human intervention – do they occur?
The answer is: not quite. No truly purple rose colors are found in the wild. The closest examples are certain wild roses with very dark pink, maroon, or deep crimson blooms. But these still lack blue pigments and the vibrant purple tones seen in hybrids.
Some damask rose varieties display very dusky mauve or lavender blooms. And a few old European rose cultivars, like the 16th century “Purple Gallica” rose, show an enigmatic grayish purplish shade.
However, no roses with brilliant blue-purple hues like the genetically engineered varieties occur naturally. The necessary biochemistry and genetics simply are not present to synthesize delphinidins.
So in summary, while lovely darker pink or lavender examples exist, true vivid purple roses remain creations of human hybridization and bioengineering. The legends of purple roses through history reflected their absence in nature.
Creating Purple Roses Today
Now that creating purple pigments in roses is possible, purple has become a popular color in rose breeding programs and the floral industry. Today, purple roses typically fall into three main categories based on production method:
Genetically engineered – As described above, transgenic roses that synthesize delphinidins via an inserted gene produce the truest purple blooms. But genetically modified organisms also attract controversy, so these roses are less common.
Hybrids using conventional breeding – Hybridizers can breed very dark pink or lavender roses by optimizing pigment chemistry without genetic modification. The results aren’t as vividly purple as genetically engineered flowers but make up the bulk of purple roses on the market.
Dyed white roses – Growers can produce inexpensive purple roses by simply dyeing white rose blooms. However, dyed roses don’t have the same longevity and natural charm as bred varieties.
Conclusion
In nature, roses lack the right pigment chemistry to produce blue or vivid purple blooms – these colors only became possible through human intervention.
While lovely darker pink or lavender examples exist, true rich purple roses are the products of meticulous hybridization over decades or recent breakthroughs in genetic modification.
Yet the allure of purple roses throughout history shows these man-made flowers fulfill a timeless wish for beauty and novelty that nature alone cannot satisfy. With science, we’ve turned the myth of the purple rose into a reality.
