Eastern Skunk Cabbage in Bog and Water Gardens

Eastern skunk cabbage is a coarse herbaceous plant native to swampy areas in northeast America from Nova Scotia, Ontario and Quebec south into Tennessee and North Carolina, plant hardiness zones three through seven. It is one of the earliest and most unusual blooming native plants. Eastern skunk cabbage can be one of the most rewarding though challenging plants to establish in a bog garden or at the edges of a water garden.

Early Spring Emergence

Skunk cabbage flowers begin to emerge through snow and ice any time from late February to April (Figure 1). They can do this because skunk cabbage is a thermogenic plant, one of a few plants that can generate intense heat. It can maintain temperatures as much as 86° F higher than the surrounding air (15°C when air temperature drops to -15°C).

Flowers of Skunk Cabbage

The only way to see the small petal-less flowers of skunk cabbage is to kneel down and peer into its inflorescence (the flowering part of the plant) spathe and spadix (Figure 2). The spadix, a short stubby structure, protects flowers embedded in its flesh and is surrounded by a leather-like hooded spathe, colored maroon with yellow or green speckles. The entire spathe and spadix inflorescense stands twelve inches or less in height.

Flowers consist of four sepals, four stamens (male pollen-producing parts), and one pistil (female part) with a stout, long stigma (pollen receptive part) above the ovary (seed-producing part) buried in the spadix (figure 3). After pollination, seeds mature in the fleshy spadix.

Pollination

According to Roger S. Seymour, Environmental Biology Department, University of Adelaide, Australia in “Temperature Regulation by Thermogenic Flowers,” September, 2006, Plant Physiology OnLine, Fourth Edition, heat seems to be part of the way insects find and pollinate skunk cabbage. Heat helps release the plants’ insect-attracting odors, in the case of skunk cabbage a rotting meat stench. The plant’s smell mimics carrion on which the insects, such as carrion beetles and flesh flies, feed and lay their eggs. Heat also keeps insect pollinators warm, important for insects forced to use a great deal of energy for this. Heat-generating flowers ‚”are like nightclubs for beetles,” observes Seymour.

Form and Structure

Eastern skunk cabbage reproduces by hard, pea-sized seeds (Figure 4) that fall by the end of the growing season from the disintegrating spadix into mud where they germinate. Floods or animals may carry seeds away from the parent plant.

Contractile roots that may be as thick as a pencil expand and tighten as they grow into the mud (Figure 5). They pull the vertical rhizome (underground stem), so the plant effectively grows down instead of up. Plants grow deeper each year, so that older ones are almost impossible to uproot. According to the 2009 VNP Society Wildflower of the Year Brochure, individual skunk cabbage plants can live as long as a century.

Leaves emerge in a rosette from the tip of the rhizome later than the spathe and spadix. They possess thick petioles and the light-green, egg-shaped leaves can extend one-half yard or more in length. With their feather-like venation, leaves look like very large Hosta leaves and in native settings are also confused with false hellebore (Veratum viride).

In the Landscape Garden

Skunk cabbage plants need water and an acidic muck in order to survive. Its roots must reach the water table. Skunk cabbage needs to be near a pathway or other vantage point for the emerging inflorescence and minute flowers to be seen and appreciated. However, correct and adequate spacing is essential because mature leaves need at least one yard in which to spread. Place skunk cabbage in its permanent position because this plant resents disturbance.

The 2008 VNP Society Wildflower of the Year is discussed in:

• VA Spiderwort in Natural Gardens: Tradescantia virginiana – VNPS 2008 Wildflower of the Year