That’s neat! I thought as I got down onto the snowy ground for an eye-level look at a sprig of wintergreen. It was standing so elegantly there in the freshly fallen snow with its single bright red berry that I just had to get a good look at it and, of course, take some pictures.
I had no idea what surprise awaited me. That came later after I was down off the mountain and back home and was looking at my photos. That’s when I noticed a caterpillar on the wintergreen’s stem. Seeing that caterpillar (that I had missed) totally caught me up in the secret world of the wintergreen. I guess it flipped a switch in my mind from That’s neat! to WHAT ELSE HAVE I MISSED ABOUT WINTERGREEN?
So, I went out the next day to see that caterpillar with my own two eyes. It was gone. I hunted and hunted on nearby wintergreen for that caterpillar or anything feeding on the wintergreen. I did find one case-bearing caterpillar hanging under a wintergreen leaf. Did it feed on the wintergreen? There’s a good chance it did. Interestingly, I had seen one of these tiny caterpillars carrying its similarly-shaped leaf case along a stem of mountain laurel one other mild winter day.
As I hunted for that caterpillar on the wintergreen, I saw lots of window-feeding sign on the wintergreen leaves. Many of the chewed spots were brownish and dried-up-looking. However, numerous ones had a tinge of green, which seems to me was evidence of relatively fresh feeding sign even though it was December. I noticed several different patterns of feeding signs, which indicated to me that several species of herbivores feed on the leaves.
I had often seen feeding sign on wintergreen, but had never seen any critters feeding, and I can’t believe I hadn’t researched wintergreen’s story before. It’s a wonder I didn’t, because I have always noticed wintergreen—to me they are like old friends that stand out in a crowd.
Anyway, back to the secrets of the wintergreen. Wintergreen’s chemical defense is wintergreen oil or methyl salicylate. The Creator gave this volatile chemical many functions:
- The “minty” flavor deters some critters from feeding on the wintergreen. Think about it… not everyone likes teaberry ice cream or Pepto-Bismol.
- When herbivores (like my missing caterpillar) feed on the wintergreen, the volatile scent is released, which calls in insect predators.
- The release of the wintergreen’s volatile scent also warns the other nearby plants to up their defenses.
- Wintergreen oil has some antimicrobial properties.
- We use wintergreen for flavoring and medicinal uses.
- Methyl salicylate is also produced by other plants such as birch, meadowsweet, willow, and some vegetables.
One day I pulled up a sprig of wintergreen to see another one of wintergreen’s secrets. What I wanted to see was its roots and their fungal partners. When I pulled up the little shrub, along came a long piece of its underground stem (called a rhizome). I rinsed the rhizome under a spigot and cut off some of the fine hair roots (not the same thing as root hairs) to look at under my microscope. At 400x and 600x magnification, it was really amazing to see those hair roots covered with fungal strands (hyphae) and to see how the fungus had grown into some of the root’s cells and filled those cells with fungal coils. What I was seeing was one of the secrets to how wintergreen thrives. They partner with mycorrhizal fungi (ericoid mycorrhiza or ErM for short). Basically, what happens is the wintergreen trades minerals and other necessities from the fungus for carbohydrates from photosynthesis.
Well, those are some of the secrets of wintergreen I’ve found out about so far. I’m expecting to have better success finding caterpillars feeding on wintergreen by going out on the mountain some dark night and crawling around with a headlamp. Doesn’t that sound like an adventure? If so, I suspect anytime you see wintergreen, they will seem like old friends and you will think, I know them! They live in such a neat, secret little world down there.