Scientific name: Symplocarpus foetidus
Common name: Skunk Cabbage
(Information in this Species Page was compiled by Rachel Lang in Biology 220W, Spring
2006, at Penn State New Kensington)
Skunk cabbage (also called “clumpfoot cabbage”, “swamp lantern”, and “polecat weed”) is a large, flowering plant of wetlands. It is a member of the Arum plant family (which also includes Jack-in-the-Pulpit and some philodendrons). It is found in wet woodlands, marshes, and alongside streams over most of the eastern and Midwestern sections of United States and Canada north of the Carolinas and south of Nova Scotia).
The tall, distinctive, enveloping spathe of S. foetidus arises from the ground in late February or early March often pushing up through the covering snow. This structure is typically the first sign of plant life in the woods after the long, gray, winter season. The spathe (which is a highly modified leaf) is brownish-purple and often streaked with yellow and red. Through the folds of the spathe, you can see the cluster of yellow flowers (the spadix) and can appreciate the extent of the protective encasement around it. The other leaves unfold in a broad spiral from the base of plant after the structure of spathe has faded. These leaves are green and quite long and broad (anywhere from 2 to 4 feet long and up to 1 foot wide). The above ground mass of the plant can stand 3 or 4 feet tall and spreads out to over-cover a substantial square footage of the soil surface.
At the center of the plant there is a short, round central root mass (a rhizome) out of which the leaves arise and from which the extensive root system forms. The roots are each about a quarter of inch in diameter and extend out from the rhizome mass in large numbers and in all directions. They grow unbranched for several feet and then terminate in an extensive system of fibrous rootlets. They solidly anchor the plant into the often loose, mucky soil. It is very difficult or even impossible to pull or even dig a skunk cabbage out of its soil foundation. The roots have circular surface ridges which grab onto the soil matrix and via root contractions actually help to pull the growing plant deeper and deeper into the soil system. Older plants, then, are rooted more deeply than younger plants. This contractile root adaptation may also help to prevent frost heaving of the plant out of the freezing and thawing wet soil matrix. The root system has been described as being “virtually indestructible” and may persist for decades and, possibly, even hundreds of years. The roots are also important storage sites for the accumulated polysaccharides from photosynthesis. These energy molecules are used by the plant each year for its flowering and growth and also for the production of heat (described below).
A Warm - Blooded Plant!
Skunk cabbage begins its yearly cycle on our Nature Trail in late February. The column of flowers (the spadix) and its enveloping spathe push up through the snow and ice down in a small wetland by the stream near the bridge. The plant is able to push up through the frozen soil and snow and maintain its tissue integrity even in very cold air temperatures because of its ability to metabolically generate heat. The spadix is the center of this remarkable catabolic event. Enzymes (“alternative oxidative enzymes” (AOX)) use atmospheric oxygen to rapidly breakdown stored root polysaccharides with the subsequent generation of heat. During the two weeks or so of spathe emergence and spadix flowering, a skunk cabbage plant will use as much oxygen as a comparably sized mammal in order to keep this heat generation system running. Further, the spadix is able to homeostatically control the activity of AOX through temperature monitoring and can, thus, keep its intra-spathe temperature not only up to 20 degrees C warmer than the surrounding environment but can also keep this temperature constant and optimal for flower maturation and pollination. The skunk cabbage is, then, a “warm-blooded” plant!
The warm micro-environment inside the spathe along with the foul odors produced by the spadix flowers (odors reminiscent of rotting meat or decaying carcasses….these odors are the obvious source of both the plants many common names and also its scientific species designation) attracts the earliest flies and hymenopterans of the forest ecosystem. These flying insects crawl into the opening of the spathe and move across the floral parts of spadix. These floral parts develop sequentially with the lower female (ovule producing) parts maturing first and the upper male (pollen producing) parts maturing only after the ovules have been pollinated. This sequencing prevents self-pollination and facilitates and sustains the intermixing of genetic material and the overall genetic diversity of a population.
Flower and Fruit
The flower forms a fruit head after pollination. The surrounding spathe withers away exposing the 2 inch or so diameter ball. This fruit head is often the same reddish to brownish purple color of the spathe. This is also the time when the green leaves of the plant unfurl around the central fruit head. In late summer these fruit heads crumble and deposit their berry-like fruits on the ground around the fading leaves of the plant. These berries may decompose in the wet soil or be eaten (by a number of species including wood ducks, ring-necked pheasants, ruffed grouse, and bobwhite quail). Only a very small number will germinate, either in the fall or in the next spring, to form new skunk cabbage plants.
The leaves and stems of the skunk cabbage are quite fragile and lack substantial amounts of woody, supportive tissue. The leaves begin to decompose on the standing plant through the summer and are so insubstantial that they make very little persisting leaf litter around the central rhizome. The leaves when crushed emit the same foul odor as the flowers. These leaves are also rich in calcium oxalate crystals which are irritating and may even be toxic if ingested. Both the odors and the presence of the calcium oxalate crystals greatly inhibit herbivory on the skunk cabbage leaves. Some animals, though, (like black bears, Canadian geese, and ring-necked pheasants) have been observed consuming these leaves especially when the leaves are young and just unfurling in the spring.
Skunk cabbage has been used in a variety of folk medicine traditions. Native Americans dried the leaves and used them to facilitate the healing of skin wounds. They also crushed the leaves and inhaled the vapors to relieve headaches. European settlers used the plant as a contraceptive agent ingesting small amounts of skunk cabbage leaves daily in the belief that the dosage would reduce fertility. In the 19th Century the United States Pharmacopeia listed the uses for skunk cabbage as treatments for asthma, epilepsy, coughs, and rheumatism.