A smelly but welcome winter plant: skunk cabbage

They don’t call it skunk cabbage for no reason! I still remember being warned off the plant as a youngster. While it seemed to me to only have a heavy oniony smell, many compare it to skunk or rotting meat. Remembering the Amorphophallus at the New York Botanical Garden last fall, you might wonder if there is a whole world of plants with terrible scents pollinated by flies. Probably more than we imagine. The scientific name for skunk cabbage is Symplocarpus foetidus with foetidus being Latin for fetid—having a heavy and offensive odor. Other plants where foetidus is part of the scientific name include Helleborus foetidus and the spice asafetida. Examples of other plants that are pollinated by flies include the paw-paw tree (Asimina triloba) and the red trillium (Trillium erectum). And we have midges to thank for pollinating cacao trees (Theobroma cacao).

Last year, around this season, I happened to be in Sprain Ridge Park off Jackson Avenue in Yonkers. Right at the entrance, there is a boggy area and poking through the mud and water, were these small curved dark green spathes speckled with purple. Because of the ooze, one couldn’t—and probably shouldn’t—walk near them but a long lens on a camera is a wonderful thing. I checked several times this year and the plant is popping up all over. And since it is a native plant, the New York Botanical Gardens has specimens in the Native Plant Garden.

The skunk cabbage relies on several insects for pollination—scavenging flies, stoneflies (which seem to spend their lifecycle near water) and bees. But isn’t it too cold for insects now? Apparently, “winter” stoneflies actually emerge and reproduce during the fall and height of winter. And I have noticed that when we have a sudden warm spell during deep cold, there are swarms of small insects. How does a plant form leaves and fruiting structures when the weather is so cold? In this case, the leaf cones and the presumptive flowering structures, are formed in the summer and lie within the crown of the plant waiting for the days to start lengthening. Again, like the Amorphophallus, the female structures grow higher on the spadix than the pollen—producing anthers and they mature earlier so that self-fertilization is generally avoided. Seeds are formed and fall in the vicinity of the mother plant where they will grow into a new baby. Later, skunk cabbage foliage will provide food for the caterpillars of the Phragmatobia fuliginosa—the Ruby Tiger Moth. These larvae will feed later in the season on dock, goldenrod, Joe-Pye weed and other plants. This moth is found throughout the northern United States and the adults can be seen April through October. However, most animals avoid eating the leaves of skunk cabbage because of the irritating calcium oxalate crystals. 

There is also one species of western skunk cabbage—Lysichiton americanu—which grows from the west coast as far east as Wyoming. It was introduced as a bog plant into the United Kingdom in 1901 and has naturalized in England and Ireland. Like the Amorphophallus, skunk cabbage is an arum- Family Araceae. Those are the jack-in-the-box plants with a cobra-like hood (spathe) surrounding the flowering stalk (spadix). Many articles say that flowering is accompanied with an noticeable smelliness while the odor noted in the name only occurs when a leaf is broken. 

There are two other fascinating features to know about skunk cabbage: contractile roots and thermogenesis. Contractile roots mean exactly what the terms implies. These roots are usually plump and fleshy and actually pull the plant crown deeper into the mud with each passing year. The root system becomes increasingly massive and sinks deeper into the mud each year making it practically impossible to remove a plant completely from its bed.

Thermogenesis means raising the body temperature above that of the surrounding air which we are familiar with from warm-blooded animals. While not unique to skunk cabbage, it is unusual. Two other plants that can create their own heat are Philodendrum selloum and Nelumbo nucifera. While the period during which plant temperatures are elevated generally lasts only a few hours or days, skunk cabbage can maintain a temperature of 59 to 71 degrees Fahrenheit while the ambient temperature is 5 to 50 degrees Fahrenheit for over two weeks. The purpose of this warmth may be to vaporize the flower scent in order to attract the pollinators who then enter the protected hollow created by the surrounding spathe.

Winter is not a gardening season, but nature is not asleep. There is more going on underneath our eyes than we ever imagined!