The color of lavender stems primarily from anthocyanin pigments in the flowers. Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway in plants.
What makes lavender purple?
The purple color of lavender flowers comes from anthocyanin pigments. Anthocyanins are a type of flavonoid, which are compounds produced by plants through the phenylpropanoid metabolic pathway. There are over 500 naturally occurring anthocyanins that provide the rich blues, purples, and reds of many fruits, vegetables, and flowers.
Specifically, the anthocyanins responsible for the purple color in lavender are:
- Cyanidin
- Peonidin
- Delphinidin
- Petunidin
- Malvidin
The relative concentrations of these pigments determine the exact hue of purple. For example, a higher amount of malvidin results in a bluer purple.
In lavender flowers, anthocyanins are present mainly in the upper epidermal layer. They appear purple due to their interaction with other pigments in the petal cells and the vacuolar pH.
Why do anthocyanins make flowers purple?
Anthocyanins appear purple, red, or blue based on their molecular structure and the pH of the vacuoles (plant cell compartments) where they are stored. Here’s a quick explanation of why:
- The anthocyanin molecule consists of an aromatic ring linked to a positively charged oxonium ion. This makes the molecule colored.
- Depending on pH, the oxonium ion may lose a proton and become neutral. This causes a color change from red to purple to blue.
- More acidic vacuoles (lower pH) cause anthocyanins to appear more red. More alkaline vacuoles (higher pH) cause them to look blue.
- Plant cells actively maintain the pH of vacuoles to fine-tune anthocyanin color.
So in summary, the molecular structure interacts with vacuolar pH to determine anthocyanins’ visible color. Lavender flowers contain anthocyanins stabilized in slightly alkaline vacuoles, making them appear purple.
Do all lavender species have purple flowers?
The most common lavender species grown for ornamental purposes or oil production have signature purple flowers. These include:
| Lavender Species | Flower Color |
|---|---|
| English Lavender (Lavandula angustifolia) | Purple |
| French Lavender (Lavandula dentata) | Purple |
| Spanish Lavender (Lavandula stoechas) | Purple |
| Portuguese Lavender (Lavandula latifolia) | Purple |
However, there are over 39 known species within the Lavandula genus. Some less common varieties have different natural flower colors, such as:
- Lavandula viridis – Greenish-yellow
- Lavandula lanata – Grayish-blue
- Lavandula multifida – White
So in nature, not all lavender species are purple. But the most widely grown types with fragrant oil-producing flowers are naturally purple from their anthocyanin content.
Can you change lavender’s flower color?
Since the pigments responsible for lavender’s purple hue are anthocyanins, altering their content or stability can modify the color.
Some ways lavender flower color can be intentionally altered include:
- Breeding – Cross-breeding light colored species with purple varieties.
- Genetic modification – Inserting or silencing genes affecting anthocyanin synthesis.
- Acid/base treatment – Increasing vacuolar pH with bases makes flowers more blue.
- Light conditions – Excess sunlight degrades anthocyanins, causing lighter color.
- Water stress – Dehydration degrades anthocyanins, causing lighter color.
However, even with genetic or environmental manipulation, lavender flowers generally remain in the purple, blue, or pink color range due to their inherent anthocyanin content.
Why are anthocyanins purple?
Anthocyanins appear red, purple, or blue based on the pH conditions where the molecule is located. Here is a closer look at why:
- The anthocyanin molecule consists of an aromatic ring bonded to a positively charged oxonium ion.
- In acidic conditions, the oxonium ion retains its proton, causing a red color.
- In alkaline conditions, the oxonium loses its proton and becomes neutral, causing a bluer color.
- In between acidic and alkaline, the partially positive charge causes a purple color.
- Cells actively control vacuolar pH to fine-tune anthocyanin color.
For example, the most abundant anthocyanin in lavender flowers is malvidin. Its aromatic ring structure interacts with cell conditions to make it appear purple.
So in summary, anthocyanins reflect red, purple, or blue light because their molecular charge is affected by pH. The optimum conditions in lavender vacuoles make the anthocyanins look purple.
How is lavender naturally purple if other species are different colors?
Lavender’s iconic purple color comes from its inherent anthocyanin composition and vacuolar pH environment:
- Popular lavender species contain five major anthocyanins: cyanidin, peonidin, delphinidin, petunidin, and malvidin.
- The slightly alkaline pH of lavender flower cell vacuoles causes these pigments to appear purple.
- Breeders select for deep purple hues when developing ornamental lavender varieties.
- Other lavender species with different anthocyanins or vacuolar conditions appear green, gray, or white instead of purple.
So the well-known lavenders from the Lavandula angustifolia, Lavandula dentata, Lavandula stoechas, and Lavandula latifolia species are naturally purple due to anthocyanin content and cellular environment – not dyes, artificial breeding, or genetic modification.
Their signature flower color is an inherent result of the flavonoids synthesized through their phenylpropanoid pathway and maintained in the flower vacuoles.
Can you breed a lavender with no anthocyanins?
It is highly unlikely that a lavender species could be bred to produce flowers completely lacking in anthocyanins through conventional cross-breeding.
Here’s why:
- Anthocyanin synthesis is controlled by multiple genes spread across lavender chromosomes.
- Completely eliminating anthocyanins would require blocking multiple steps in the phenylpropanoid pathway.
- Flowers serve to attract pollinators, so color is evolutionarily advantageous.
- No natural lavender mutations completely lacking anthocyanins are known.
The only current way to potentially generate lavender flowers with no anthocyanins would be through advanced biotechnology techniques such as:
- Targeted genome editing to disable anthocyanin synthesis genes
- Inserting silencing genes to block anthocyanin production
- Engineering alternate pigment pathways like carotenoids
However, GM lavender is not commercially available. So practically speaking, even white lavender varieties retain some low levels of anthocyanins to generate pale coloration.
Do purple varieties produce more essential oil?
There is no direct relationship between flower color and essential oil content in lavenders. Purple varieties do not necessarily produce more oil than white or pink flowering types.
Factors that influence lavender essential oil yield include:
- Species/Cultivar genetics
- Growing conditions – soil, water, sunlight
- Harvest time
- Extraction method
Flower color depends on anthocyanin content localized in the petals. However, lavender essential oils are synthesized and stored in glandular trichomes on the leaves and stems.
So while flower color variation can indicate breeding lineages, it does not directly correlate to oil production capacity. Properly grown varieties of any natural flower color can produce abundant oil.
Conclusion
In summary, the iconic purple color of lavender flowers comes from anthocyanin pigments synthesized through the plant’s phenylpropanoid pathway. The aromatic structure of the anthocyanin molecules interacts with the slightly alkaline pH environment of the vacuoles to appear purple. This color is a natural product of lavender’s genetics and biochemistry, not artificial dyes or breeding modifications. While other species may have different hues, the common ornamental and culinary lavenders will always be radiant purple!
