Field Notes—

Stinky Skunk Cabbage Anchored By Ancient Roots

By Dottie Evans

Remember when we were kids digging in the back yard, thinking if we kept going we’d reach China?

Well, skunk cabbage that is just now poking its purple-spiked hood through last year’s leaves have roots that are headed in the same direction — straight down. With every passing spring, those roots have been growing deeper and deeper, and anyone foolish enough to try digging them out would have to admit it is a complete waste of time.

But we can’t see what skunk cabbage roots are doing. It’s the hooded bud and the green leaves we enjoy watching, mainly because their appearance in our wetlands is as reliable a predictor of spring as robins, crocuses, and snowdrops.

Even as children, we knew how to find the wettest, lowest, muddiest places where it grew, and we knew that mashing its green leaves released a truly horrible, putrid, gag-inducing odor. Waving the stinky pulp under a friend’s nose never failed to produce yells of outrage.

Only as we grew older, perhaps in high school biology class or in college, did we learn there was a purpose for everything in nature and that skunk cabbage smells bad for a good reason. Its carrion smell served to attract insects that would crawl or fly into the protective hood (called a spathe) where they would rub against the single, yellow flower hidden inside and pollinate it.

Flies, gnats, spiders, even a few bees — all are attracted. But it’s not just the smell of rotting flesh that draws them in. It’s also the heat. One could almost say that, in a way, skunk cabbage is warm-blooded, because it has the ability to raise its own temperature.

If you don’t believe me, get down on all fours, eyeball to spathe with Simplocarpus foetidus and poke your finger inside the fleshy hood. Touch the yellow flower bud. If there’s a contrasting chill in the air, you’ll feel actual warmth.

Biologist Roger Knutson was the first to discover that skunk cabbage flower buds can produce palpable warmth up to 60 degrees F, although the air/ground temperature may be at or below freezing. The process by which heat is produced as the result of vigorous growth and cellular respiration is called thermo-genesis. Visible proof of it lies in the gradual melting of snow or ice that immediately surrounds the plant.

While skunk cabbage raises its gnomelike head for a week or two, the gradual unfolding of the lush green leaves is what transforms the forest floor. And as hard as those leaves are working to gather early spring sunlight for photosynthesis, the roots are working just as hard to pull the whole plant back down again into the mud.

Here’s how it works. Skunk cabbage roots are contractile. They are wrinkled and have ring-shaped nodes not unlike the flexible tubing that we use to vent clothes driers. When sucking up water and energized by nourishment supplied by the leaves, the roots grow rapidly downward and the rings contract. This pulls the plant’s crown ever deeper into the damp earth, where it will be remain protected until next year’s emergence.

Though reproduction is by seeds that drop in the mud, it’s the potential age of a single skunk cabbage plant that induces awe. Botanists believe that growing in an undisturbed, muddy bed, individual skunk cabbage plants might survive for hundreds, even thousands, of years.

Think about it. Skunk cabbage that you notice today while walking in the woods might have been growing in that spot since the last glacier melted.

All those springs over so many centuries and millennia. So much time for the roots to burrow deeper down — maybe going all the way to China.