Skunk cabbage rules the winter wetlands

The annual “swamp stomp” at Jug Bay Wetlands Sanctuary is a wet, midwinter hike along the forested edge of the Patuxent River in Anne Arundel County, MD. For hike leader and sanctuary volunteer Siobhan Percey, it’s a pilgrimage of love — for the quirky, cunning and sometimes malodorous wetland plant known as Eastern skunk cabbage.

“It’s a good excuse for getting out of the house in the winter, and it’s something unique to see and learn about,” Percey said. “It’s really fascinating.”

Skunk cabbage has found a niche in the unique ways that it grows and multiplies. The formula is so successful that the plant has changed little since it came into being more than 72 million years ago, during the Cretaceous Period. Jug Bay is home to thousands of skunk cabbage plants in several different patches.

“Even though there’s a typical appearance, they are also very varied. It’s a bit like a treasure hunt,” Percey said.

Skunk cabbage can be found in wet areas along springs, streams and rivers throughout the Chesapeake region. In late spring and early summer, those who don’t know it by name might still recognize the distinctive colonies of low-growing plants, often 2–3 feet wide with broad, whorled leaves, and by the odor they emit when the leaves are damaged. 

But a year in the life of skunk cabbage begins months earlier, in January, in a much different form.

In spring and summer, large colonies of skunk cabbage are easy to spot in moist ground along springs, creeks and rivers. Their winter emergence is more subtle. (Dave Harp)

The plant breaks ground as a flower, but not the showy kind. It pokes through the muck and the snow with a thick, mottled purple leaf called a spathe, which grows into an upright hood that encloses the flower, called a spadix. 

The spadix takes female form first, resembling a small purplish pineapple, followed by a yellow male form with stamen. By rotating the sex of its flower, Percey said, the plant avoids self-pollination and maintains a genetic advantage.

After sprouting, skunk cabbage must then attract pollinators — in the middle of the winter, in a swamp — so it generates heat. While some plants are known for this trait, far fewer can regulate their own temperature. The skunk cabbage adjusts its temperature as needed to maintain an interior of approximately 60–70 degrees Fahrenheit.

The heat melts the snow around its base and defends it against frost. But the heat also attracts tiny flies that do the work of pollination, warmly ensconced by the walls of the spathe. The heat also produces the plant’s trademark odor as an added lure for the flies.

“The reason for heat production is to draw in those insects to that little hood and flower structure, and reward the insect for going in. It also delays the insect so it can collect the pollen and spread it to the next plant,” Percey said.

If the plant is pollinated successfully, the flower transitions to a fruit with approximately 20–30 seeds about the size of chickpeas. They contain calcium oxalate crystals, making the plant distasteful and even toxic if consumed in the right amount. 

This means that animals won’t raid the plants for seeds, but animals won’t help spread the seeds through their digestive systems either. Instead, the weighty seeds fall at the feet of the mother plant and create colonies. One established skunk cabbage at Jug Bay had 17 first-year plants growing at its base.

As the plant grows, usually in damp soil, it develops contractile roots, which shrink to pull the plant deeper into the soil over time. By August, the leaves are gone, and the roots are all that remain until the cycle begins again, possibly beneath the cover of snow.

Henry David Thoreau, an early American writer and philosopher, made note of skunk cabbage for its unusual features as well as its metaphorical message. “If you are afflicted with melancholy at this season, go to the swamp and see the brave spears of skunk-cabbage buds already advanced toward a new year…” Thoreau wrote in his journal. “See those green cabbage buds lifting the dry leaves in that watery and muddy place. There is no can’t nor cant to them. They see over the brow of winter’s hill. They see another summer ahead.”