A West Coast Mystery: The Butterscotch Tree, aka Jeffrey Pine
We Californians have our very own arboreal enigma: the resin of the Jeffrey Pine. If you hug a large Jeffrey, and put your nose in a deep furrow in the bark, you will smell--believe it or not--butterscotch! What the dickens is in Jeffrey resin that makes it smell so yummy? Perhaps we can get a clue from butterscotch recipes.
If you want to make your own butterscotch from scratch, you'll need three ingredients for that distinctive butterscotch aroma: brown sugar, real butter, and vanilla. Of course, the molasses in the brown sugar is the primary contributor to the aroma. Real butter contributes the chemical diacetyl, and trace trace amounts of free butyric acid. (In higher concentrations, the latter has a very unpleasant smell.) And there are probably other chemical aroma contributors--of which I'm not aware--in the three basic ingredients.
There are some interesting coincidences in the varying olfactory perceptions of my fellow hikers.
I'm in a minority of hikers who smell butterscotch in Jeffrey resin. But most hikers smell vanilla. And vanilla is a key ingredient in butterscotch aroma.
A very small minority of hikers smell pineapple in Jeffrey resin. Interestingly, the butyric acid (in butter) is a moiety of the ethyl butyrate molecule, the essence of pineapple flavor.
Here's a link to Hubpages author DixieMockingbird's recipe for butterscotch filling.
Speaking of recipes... The hiker who smelled pineapple in the Jeffrey resin gave me an idea for a quickie dessert. How about butterscotch pudding with a pineapple slice? No, I have not tried it yet.
Does the Jeffrey Pine produce equivalent chemicals?
Or is there a single chemical in Jeffrey bark that hits all of these receptors in our noses? If so, it's possible that the surface of each region of the mystery molecule contributes a different aroma component, and that together, they all add up to butterscotch. That would be very interesting if true.
A second question: What is the survival value--if any--for the Jeffrey emissions? From my perspective, the Jeffrey Pine is sending out a very clear olfactory message: Eat me! Fortunately for the Jeffrey, Pine Bark Beetles don't have my finely honed olfactory sense.
Jeffrey Pine trivia
As I mentioned earlier, Jeffrey Pines grow mainly in California. However there's supposed to be a very small Jeffrey zone near the SW corner of Oregon.
If you drive East on Highway 50 from the Sacramento metro area, you'll go mostly beyond the oak zone, and then you'll be up in the mixed conifer zone--including Jeffrey Pines--when you get above 5000 feet elevation (1500m).
The bark of the Jeffrey Pine has a dark reddish tinge. And a mature Jeffrey has deep furrows in between large plates.
The ranges of Jeffrey Pine and of the similar-appearing Ponderosa Pine overlap considerably. You can see both species near the Western shore of Lake Tahoe. How does a non-botanist (like yours truly) tell them apart?
According to a hiking friend, the most obvious difference is in the cones that you find under these pines. On Ponderosa cones, the sharp parts point out. On Jeffrey cones, the sharp parts point inward. Here's a memory aid: Prickly Ponderosa and Gentle Jeffrey.
In contrast with the Butterscotch Conundrum, there's a well-known piece of Jeffrey Pine chemistry. The resin contains a very high concentration of n-heptane. Petroleum also contains this hydrocarbon, mixed in with lots of other hydrocarbons. Apparently it's cheaper to extract high purity n-heptane from Jeffrey Pine resin than it is to do repeated fractional distillations from petrol.
N-heptane is useful for calibrations when you're researching octane ratings of various motor fuel formulations. N-heptane is such a poor motor fuel that it's assigned an arbitrary octane number of zero.
Speaking of n-heptane... The Wikipedia article on the Jeffrey Pine suggests--but does not explicitly state--that it's the heptane that contributes the butterscotch aroma to the resin. I'm very skeptical about that. N-heptane is a hydrocarbon skeleton without any meat on its bones. It does not contain any of the 'functional groups'--like the COOH carboxylic acid group--that make organic chemistry interesting.
But the Wikipedia article on n-heptane does not mention butterscotch or vanilla. So much for the inerrancy of Wikipedia. :)
So far, we know two things about Jeffrey Pine chemistry: the butterscotch aroma and the n-heptane. Let's put the two pieces of the puzzle together, and see if we can explain the question about survival value that I raised in the first section. Here's my wild hypothesis: Jeffrey Pine emissions are a means by which these trees communicate with each other.
A reasonable ratio of the butterscotch aroma in proportion to the n-heptane is a message to other Jeffrey Pines in the neighborhood:
Hello world! I'm a Jeffrey, and I'm in reasonably good health.
But if the proportion of butterscotch dips below a threshold value, the message becomes:
I'm a Jeffrey, and I'm under attack by Pine Bark Beetles. You'd better marshal your defenses immediately!
This is in addition to the generic role that jasmonic acid and its derivatives play in plant defenses. I'm guessing that the unique chemicals in Jeffrey resin are useful in defending against Pine Bark Beetles, and for 'alerting' other Jeffreys to the presence of these beasties.
Hey, hold your horses! Trees sending chemical messages? Yes, Hubpages author Nell Rose has written an outstanding article about the senses of trees and other plants. And some of these senses--together with plant pheromones--play a role in simple communication between plants.
By the way, my hypothesis is probably incorrect. I'm open to other ideas on the subject.
The main point is that there are reasons for the butterscotch aroma and for the n-heptane in Jeffrey resin. Proper scientific investigation could unlock the secrets of Jeffrey Pine chemistry.