Diggin' In: The odd but useful life of the skunk cabbage

March 9, 2015

When you hear the name, skunk cabbage, you instinctively wrinkle your nose, thinking it smells bad.

You’re so right. This first flowering plant of spring doesn’t exactly smell good.

"The flowers of skunk cabbage have no colorful petals to attract pollinating insects," says Helen Hamilton, of the native plant that flowers in winter. Hamilton is author of "Wildflowers and Grasses of Virginia’s Coastal Plain "Instead, they emit an odor similar to decomposing flesh which attracts the first insects of the year, usually carrion and dung flies, but also beetles, bees and mosquitoes."

Skunk cabbage, or Symplocarpus foetidus, produces a purple-brown and green mottled hood, which is a modified leaf called the spathe, two to five inches long, according to Hamilton. Inside is a nearly round flower head, the spadix, with many small, tightly packed individual flowers.

"They ‘bloom’ when stamens emerge above the four tiny sepals," she says.

"After the pollen is released, the stamens wither, and a style grows out of the middle of each flower to be pollinated by insects with pollen from other flower heads."

The plant’s interesting behavior doesn’t stop there. Skunk cabbage is considered a "warm-blooded" plant because its spathe produces enough heat to melt surrounding snow and ice and to volatize the odor, according to Hamilton and Dr. Gustav Hall, professor emeritus at the College of William and Mary. Carbohydrates stored in the rhizomes are metabolized, raising the temperature around the flowers; the warmth remains for two weeks while flowers are pollinated.

As the spathe fades, green leaves unfold in a broad spiral from the base of the plant; when crushed, the leaves smell as bad as the flowers, according to Hamilton Without much supportive tissues, the leaves and stems begin to decompose on the plant in summer and produce very little leaf litter by fall.

Growing in swamps and moist low ground, skunk cabbage is widely distributed in Virginia, according to Hall. Its range extends from Quebec and Nova Scotia to North Carolina and west to Minnesota and Iowa.

Three other members of the Arum family, somewhat similar to skunk cabbage, are common in the Coastal Plain, including Jack-in-the-pulpit (Ariseama triphyllum), with three-parted leaves, and arrow arum or Tuckahoe (Peltandra virginica), with arrowhead-shaped leaves and a leaf-like spathe with a club-shaped spadix, according to Hall. The leaves of golden club (Orontium aquaticum) are elliptical, the spathe obscure and the spadix and its flower bright yellow, he adds.

Beneficial carrion flies

Carrion flies are members of the Calliphoridae, a family of insects with more than 1,100 known species that are commonly known as blow flies, green bottles or blue bottles, according to Hamilton. The name "blow fly" refers to the swollen condition of meat that is being eaten by larvae.

Often mistaken for house flies, blow flies are larger with green or blue metallic bodies. In North America there are 80 species of blow flies. If you see them near or in your house, it means they found a beneficial place to lay eggs — garbage, compost piles or a dead animal, like a mouse in a trap, squirrel in the chimney, a bird in the attic, etc. To control them, remove the decaying matter.

Blow flies are attracted to the rotting flesh odor produced by skunk cabbage flowers. While they gather nectar, they collect pollen on their hairy bodies and that pollen is deposited on the next flower they visit, according to Hamilton. Adult blow flies feed on flower nectar, plant sap, and other sugary substances, but their life cycle is completed on animal carcasses. Female blow flies lay their eggs on rotting meat, and maggots hatch within a few days, feeding on decaying tissues. Theses larvae then burrow into the soil and pupate, emerging later as adult flies.



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