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Appreciating the spectacular, hot-headed skunk cabbage

Minnesota is at the northwestern edge of skunk cabbage range, and it grows only in moist swampy lowlands, the kind of places where the coldest and densest air of the night settles out and intensifies its chill. 

Skunk cabbage is one of the very few plants capable of thermogenesis — of creating heat.
Skunk cabbage is one of the very few plants capable of thermogenesis — of creating heat.
Photo by Dr. Craig Bowron

The calendar says we’re officially into spring, but below-average temps have kept the leaping greenly spirits of spring at bay.

A walk in the woods will remind you of that. When the bright veil of snow lifts, the land remains in a sooty ‘fifty shades of brown’ death grip. If you see color, it’s usually litter — someone’s windblown candy wrapper, or a foil birthday balloon that escaped and crash-landed in these woods.

Then suddenly, there it is: the spectacular, deep wine-red, sometimes yellow speckled color of the genie-bottle shaped skunk cabbage flower. Inside this leafy mottled maroon hood (called a spathe) lies a fleshy spike of petal-less flowers unglamorously labeled the spadix.

The tropical-looking spathe is not only confusing (“Is that a plastic plant?”), it’s also illogical. We’re at the northwestern edge of the eastern skunk cabbage range, and it grows only in moist swampy lowlands, the kind of places where the coldest and densest air of the night settles out and intensifies its chill. 

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How can this lavish, leafy and exuberant plant grow four to six inches high without getting frozen to a crisp every subzero evening? What allows it to be the first plant out of the box every spring, often emerging right out of the snow? This seems like something only Pixar could pull off.

It turns out that skunk cabbage is one of the very few plants capable of thermogenesis — of creating heat. Back in the 1970s a scientist named Robert Knutson studied the breathing patterns (i.e. oxygen use) of skunk cabbage in northeastern Iowa and found this little wonder plant could keep the temperature inside the spathe 36 to 63 degrees above whatever the ambient temperature was. The colder the air, the hotter it needs to burn to maintain consistent warmth inside the spathe. The heating is most intense for the two-week period when the plant is actively blooming. 

As fantastical and flashy as all that is, the skunk cabbage’s only goal is to get pollinated, not to heat the neighborhood. The warmth of the spathe allows some insects, like bees, to weather the biting cold of a spring night, and fly off to visit other skunk cabbage plants in the warmth of the next day. But the plant also emits a somewhat putrid odor — hence the ‘skunk’ part of skunk cabbage. That stink attracts many of the season’s first flies and gnats, which typically lay their eggs in the thawing flesh of winter-killed animals and so are quite naturally attracted to this rancid smell.

The skunk cabbage’s only goal is to get pollinated.
Photo by Dr. Craig Bowron
The skunk cabbage’s only goal is to get pollinated.
As the spathes begin to die off and the weather warms, the leaves of the skunk cabbage appear, reaching up to three feet in size. They look like a cross between romaine and butter lettuce, but don’t be tempted: the leaves create a burning sensation that’s so bad even deer (the varmints that will mow through your entire row of hostas in under 45 minutes) don’t touch them.  

By the time the leaves on the trees overhead start to unfurl, the skunk cabbage leaves develop black spots and begin to die back and decay. 

So be patient. Spring will arrive in its own good time. It always does. If you are in desperate need of a reminder of the emerald opulence to come, tug on your mudboots and head off to moist and marshy confines where the skunk cabbage is already performing its passion play.