O Christmas Tree: Why Conifers 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 flat fronted 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 in her wake.

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 culled mainly from the forest. Now sold in venues like Target, I can no longer vouch for its authenticity. But I do recognize its signature green, pinecone-shaped bottle, a vessel that still evokes memories of a life much spicier than my own.

Pino Sylvestre ad/mavive.com

That sharp forest smell, scented pinecones and more are on 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 smell? It’s tied up in resin. Pine, spruce and fir trees 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 conifers produce resin in response to injury. But some produce it spontaneously from branches and cones. Resin can be found all over the tree — in the trunk, twigs, cones and even needles. It first appears as clear and gradually turns yellow as it ages.

Pine cones leaking resin

In its hard, fossilized form, resin is known as amber.

Amber is fossilized resin

Resin is not sap

Often confused with sap, resin is a water insoluble, sticky organic fluid that is produced in response to injury. Its role is defensive.

Sap, on the other hand, is a water-based fluid made up of sugars, hormones and other enzymes that circulates in a tree’s vascular system. Its role is nutrition.

Soft woods like conifers have more resin than hardwood. And pines have the most.

Conifers produce the most resin

On the scent

So why does conifer resin emit such a fresh, outdoors-y scent? The answer is terpenes.  A primary constituent of resin, these volatile organic compounds perfume our forests while providing antimicrobial properties that allow trees to fight fungus and diseases. Ever noticed 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 and regulate their atmosphere.

Terpenes help forests regulate their atmosphere

Different pine species have different terpene content, which affects their aromas. The resin of the North American pine, which contains a terpene also present in plants in the parsley family, is said to have a grassy aroma. Ponderosa pines, on the other hand, have a sweet-smelling terpene known as 3-carene, a major constituent of turpentine. (Turpentine derives its name from terpene.)

People have collected resin from trees for thousands of years to make all sorts of things including incense, medicines, adhesive and varnishes. But it’s conifer terpenes that make up the primary constituants of essential oils used in perfumes and aromatherapy. Terpenes can also be found in a wide variety of cleaning products, although recently humans have started experimenting with some synthetic varieties.

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. The traditional method is to notch the bark in a parallel V-shaped pattern. 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 scent of Christmas, the outdoors and Pino Sylvestre.

 

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