Why Christmas Trees Smell So Good


When I was a teen, a French girl came to stay with us for the summer. She caused quite a stir in northern Delaware with her cigarette jeans, lace-up wedge espadrilles and oversized red glasses. But what I remember most was her preference for a men’s cologne named Pino Sylvestre. Wherever she went, a fresh, forest-like scent followed behind her.

A quick Google search today reveals that the original Pino Sylvestre was sold as,

“A breath of fresh air in a bottle, uncomplicated and inviting.”

Launched in 1955 by Massimo Vidal, it consisted of a mix of 12 essential oils gathered mainly from the forest. Now sold in venues like Target, I can no longer vouch for its authenticity. But I do recognize its signature pinecone-shaped bottle, a green vial that still evokes memories of a life more fiery than my own.

Pino Sylvestre ad/mavive.com

That sweet forest smell passes through my mind this week as I head out to purchase a Christmas tree. We buy ours at the local nursery. I love the invigorating chill of the outdoor, canopied enclosure and the sight of all the conifers waiting patiently in line. And there’s that aroma again, the clear, fresh scent of pine. It hovers in the air above the trees; you could swear they were breathing.

For many of us, the smell of pines, firs and spruces is inextricably linked to the holidays and the exhilarating feel of the outdoors. In my case, it also reminds me of my younger self and life on the wilder side. Most people, though, would agree that the earthy aroma just makes them feel happy.

This is not, however, the reason why the trees produce it.

The resin behind that distinctive smell

The secret to that piney Christmas tree smell? It’s tied up in resin. Varieties such as pine, spruce and fir all produce the sticky, viscous stuff. Resin protects a tree by acting as a kind of deterrent. It wards off pests and diseases and when a tree is injured, it flows out, hardens and seals off the wound.

Amber-colored resin

Most trees produce resin in response to injury. But some also produce it spontaneously from branches and cones. Resin can be found all over the tree — in the trunk, twigs, cones and even needles. First appearing as clear, it gradually yellows as it ages. Soft woods like conifers have more resin than hardwood. And of all the Christmas tree varieties, pines have the most.

Pine cones leaking resin

In its hard, fossilized form, resin is known as amber. Because resin can flow without warning, many ancient flowers and insects have ended up being preserved in amber, providing an interesting window into previously unknown species.

Amber is fossilized resin

On the scent

So why do Christmas trees smell so outdoors-y? The answer is terpenes.  A primary constituent of resin, these organic compounds perfume our forests while providing antimicrobial properties that allow trees to fight fungus and disease. Ever notice how fragrant a pine forest is in summer? In warm weather, higher amounts of terpenes are released by trees as a natural form of cloud-seeding. This allows them to cool the forest while controlling their atmosphere.

Terpenes help forests regulate their atmosphere

Different pine species have different terpene content that affects their aromas. The resin of the North American pine, which shares a terpene with plants in the parsley family, is said to have a grassy aroma. Ponderosa pines, on the other hand, have a sweet-smelling terpene that is also a major component of turpentine. (Turpentine gets its name from terpene.)

Terpenes have been collected for ages for perfumes and aromatherapies as well as medicines and cleaning products. You may have noticed pine trees that have part of their bark stripped away and a series of deep V’s cut in their trunks. These are trees that are being tapped for resin. If done properly, conifers can be tapped for up to 20 years or more without hurting the tree.

Trees being tapped for resin

I learned later that Pino sylvestre most likely got its name from the Latin, Pinus sylvestris, commonly known as Scotch Pine. Scotch Pines are the most widely distributed pine in the world. Their excellent needle retention and bright green color has made them the most common Christmas tree in the US for decades, accounting for approximately 30 percent of the 35 million Christmas trees harvested annually.

Scotch pine aroma is generally described as herb-y, fresh and slightly grassy. Some classify it as ‘dry-balsamic.’ For me, it is the essence of that Christmas tree smell, the outdoors and Pino Sylvestre.


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