This piece is dedicated to commenter ModernGrace, who suggested in a comment on our review of May Lindstrom’s Blue Cocoon piece that “Blue tansy seems to be the ingredient of 2015. I’ve already seen it in Sunday Riley Luna Sleeping Night Oil.” Quite on the nose, Grace: three of us in the office had already been testing (and loving) the stuff, and are now obligated to tip our hats. You've trend scooped us, well done.

But back to that Luna Sleeping Night Oil (the most fairytale name you could hope for). You’ll find out why it’s reserved for sleeping—it’s really blue. Not a color-changing blue. We're talking aftermath-of-Avatar-Halloween-face-paint kind of blue. It’s suitable to nighttime not only because it contains a retinoid (!) but also because, well, a slightly aquatic tinge is not going to look so great under tinted moisturizer. Which got the three of us wondering—why is it so indelibly blue?

That’s the blue tansy, this week’s Ingredient To Know. It’s a flower—poisonous if ingested, but if you render it just right, it’s got a great medicinal range (pity the ancestors who figured this one out the hard way). Blue tansy’s most salient features are its antibacterial, antihistamine, and general anti-inflammatory nature, with a side effect of skin-calming and reaction-soothing (as you may expect). It’s got a pretty herby bouquet that announces itself assertively (but not annoyingly) to a room. How do you tell if a product has blue tansy? Don’t worry—it will find several ways to let you know.

The tansy, itself, is genetically very similar to chamomile and shares much of its sister-plant’s calming qualities. If you get just the straight blue tansy oil, you can mix a little in with your shampoo to calm an itchy scalp (although platinum blondes might want to rinse extra thoroughly). If you’re at least intermediate in the essential oils game, you can mix with jojoba oil and rub on minor aches and pains.

It’s a prominent ingredient in May Lindstrom’s The Blue Cocoon, an almost coconut-oil-feeling beauty balm that proudly wears the blue-tansy team color. Lindstrom takes full advantage of tansy’s aromatherapeutic potential, adding a few extra essential oils in the mix for an even wider range of benefits—‘calming’ being chief among them.

In the Luna Oil, tansy's been deployed equally as deftly—a star feature in a night oil whose steady and slow regenerative process is equaled only by its redness-calming properties. With an early-season showing as strong as this, we’re predicting blue tansy will be the next hero ingredient—maybe even the next argan.

And it’s worth pointing out that products with blue tansy seem to share thematic titles—Blue Cocoon and Luna? Sounds perfect for an overnight metamorphosis.

Photographed by Tom Newton. Read more about ingredients here.