Why Are Some Strains of Cannabis Purple?

purple strains of cannabis are quite unique

When a few tokes of a Purple Haze have you acting funny, the pigmentation of the purple strains’ leaves is probably the last thing on your mind as you excuse yourself to go kiss the sky.

But the characteristic purple leaves of Purple Haze and other purple strains are important to keeping track of strains’ pedigree. Further, the presence of purple pigment could prove to be an indicator of different therapeutic or psychotropic traits.

Purple strains containing visible amounts of pigment include Purple Haze, immortalized in the Jimi Hendrix classic song of the same name, as well as Grandaddy Purple, Blue Dream, Purple Kush, etc. The color distribution ranges from a bluish hue that dominates the leaves closest to the flowering portion of the plant to spidery streaks of vivid violet that follow the leaf veins.

What causes the purple color in cannabis leaves?

The purple pigment in pot plants is called “anthocyanin,” a term that encompasses a number of different configurations within a class of molecules called flavinoids.

Marijuana isn’t the only place you find anthocyanins in nature — they’re in eggplants, purple cabbage, blueberries, violets, grapes and hundreds of other edible and non-edible plant species.

Most plants, however, are green because they contain larger amounts of chlorophyll, the pigment that absorbs sunlight and allows plants to make energy through photosynthesis. Chlorophyll appears green because it absorbs the red and blue wavelengths of light from the sun, but reflects the green.

Anthocyanin, however, absorbs most of the green light and reflects back the blue, red and violet wavelengths, making it and the leaves it inhabits appear purple.

purple strains of cannabis are from the flavonoid anthocyanin

Scientists aren’t sure exactly why plants evolved anthocyanin. One theory is that it helps keep plants’ photosynthetic systems from getting too much light at once. Counterintuitively, too much sunlight can slow photosynthesis down,  so bouncing some off with purple pigment can narrow the intake and make the plant’s metabolism more efficient. 

Some growers and connoisseurs believe that when the plant is exposed to flashes of cold weather, the plant goes on to express a purple pigment. However, the mechanism of action for this is unknown.

But even if that theory were true, it’s only part of the story. Some plants, like tomatoes, turn purple as a sign of nutrient deficiency. The real evolutionary reason for anthocyanins in plants is probably more complex. Some scientists even theorize that millions of years ago, most plants were actually purple, using primitive purple pigments for photosynthesis instead of chlorophyll.

What does color have to do with the effects of a particular strain of cannabis?

Regardless of its evolutionary function within plants, anthocyanins seem to have a strong physiological effect on the human body.

“Anthocyanins may function as antioxidants, improving blood circulation and reducing inflammation, as well as having anticancer and some other special pharmacological effects,” according to a 2016 study published in the journal Plant Transcription Factors.

“Thus, the healthcare market is greatly interested in anthocyanins. Although pure anthocyanin is not sold on the market, many anthocyanin-related healthcare products exist in the form of capsules, tablets, and oral solutions. Clinically, anthocyanins have also been added to certain drugs to help patients.”

This doesn’t necessarily mean that people who consume purple strains of cannabis get these effects from the anthocyanin it contains because there are such tiny concentrations. Furthermore, marijuana users consume a tiny amount of product compared to the amount consumed, say, in a serving of eggplant Parmesan or Concorde grapes.

The color in purple strains of marijuana is probably more useful to think of as a strain-identifying tool rather than a primary contributor to the strain’s psychoactive or therapeutic effects. Purple strains don’t seem to differentiate between Sativa vs. Indica and purple stains span multiple “Activity Groups” within the WoahStork marketplace.

Do purple strains have particular effects because they are purple?

Scientists at a small consortium called The Cannabis Genomic Research Initiative (CGRI) are working on figuring out what genes in marijuana are responsible for making certain strains purple.

“We know that most Cannabis plants are not purple but green. But we don’t know exactly why some turn out purple. More research needs to be done,” writes researcher Daniela Vergara of the CGRI. “Sometimes it’s nature, sometimes it’s nurture (or as we evolutionary biologists call it: genes and environment)… Regarding the color purple, we could find out exactly where on the DNA the gene(s) that give the plants the potential to be purple is or are located.”

Armed with this information, researchers could start teasing out what other characteristics of the plant — potency, therapeutic benefits, psychotropic effects — are associated with purple coloring.


“Sweet Potato Anthocyanins”

Taihua Mu et al

Sweet Potato Processing




ScienceDirect curated research page


“Why does purple marijuana turn purple?”

Daniela Vergara and Reilly Capps

The Farm

Aug. 26, 2015


“How Does a Cannabis Strain Get Its Name?”
Jeremiah Wilhelm


About Adam Townsend 50 Articles
Adam Maxwell Townsend has been a journalist for 15 years. His reporting has covered science, technology and medicine. Currently, he edits and writes medical and pharmaceutical articles for consumer websites, including WoahStork.

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