Species Spotlight: Purple Loosestrife and Skunk Cabbage

February 18, 2022

by Kimberly Stever

Blooming purple loosestrife. C: Lesley J. Mehrhoff, University of CT, Invasive.org

Stand of purple loosestrife. Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Purple Loosestrife; Lythrum salicaria

Purple loosestrife is an invader of wetlands throughout nearly all of North America. Native to Europe, North Africa and Asia, it was likely introduced numerous times throughout the 18th and 19th century due to its use for ornamental plantings and herbal remedies as well as through accidental contamination of ship cargo and ballast.

This highly adaptive perennial prefers moist conditions and full sun, but has been known to spread to drier environments like pastures and meadows. This forb germinates in the mid spring, but rapid growth means that new plants can reach heights of 3 feet during their first year of growth. Most mature plants grow to between 6-9 feet tall. These plants have striking purple flowers that bloom from July to September and are pollinated primarily by butterflies and bees. Mature individuals can produce roughly 2 million seeds annually, which may be transported by wind, animal or human activity (particularly boats). These seeds germinate the best in moist soil and warm conditions, but a 2001 study indicated that germination is probable within a temperature range of 41° to 95° degrees Fahrenheit.

Dense growth. Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

So why should we be concerned about this fast growing wetland plant? Their high-volume seed production, height and propensity to form dense stands, means that this plant is very effective at dominating an area, shading out the understory, outcompeting other plants and greatly reducing biodiversity in general. Many rare and endangered wetland plants rely on specific conditions and a vast monoculture like that created by purple loosestrife greatly reduce the likelihood of their continued existence. These dense stands also inhibit the nesting of those migratory birds and waterfowl who rely on native wetland habitats like the least bittern and marsh wren. The condensed root systems of these plants trap sediment, which diminishes the natural water filtration that is an important aspect of freshwater wetlands. This can cause the wetlands to retain water, raising water levels and impacting certain recreational activities like hunting, fishing and boating. These root systems also negatively impact fish spawning rates and reduce the aquatic habitat of water turtles and amphibians.

The root boring weevil (Hylobius transversovittatus) one of four beetle species released in the US to help control purple loosestrife. C. Bernd Blossey, Cornell University, Bugwood.org

There are multiple methods being utilized to control the growth and further spread of this plant. Traditional mechanical methods of removal have proven to be effective, particularly for small infestations. Although care must be taken to remove the root system completely. These plants should never be cut, as the stems can re-root on moist ground. The removed plants should be burned or brought to a landfill to prevent re-establishment. Herbicides are not effective at dealing with large populations because they will impact the other wetland plant species in the area.

Four different species of beetle which consume specific parts of purple loosestrife have been released in the United States to help control burgeoning populations and have been shown to be successful at controlling large infestations. These are two species of weevil that feed on the flowers, seeds, roots and foliage and two species of leaf eating beetles.

What can you do? Learn to identify purple loosestrife and how to distinguish it from other native look-alikes like blue vervain and swamp loosestrife and be sure to report any sightings using IMapInvasives.


Skunk cabbage

Skunk Cabbage: The mottled purple hood of the spathe and the green root bud from which all the leaves will develop. C. Kimberly Stever

Skunk Cabbage; Symplocarpus foetidus

Skunk cabbage melting snow. C. Flickr user Ryan Johnson via Nature Serve

Skunk cabbage is one of the earliest perennial wildflowers to emerge and bloom. These alien looking plants favor very wet soil conditions like wetlands, swamps and marshy woods. The first thing to appear in the winter and early spring is the spathe, a mottled purple leaf which resembles a hood and encloses the spadix. A narrow opening in the side of the spathe eventually widens to further reveal the yellowy, flower covered knob of the spadix. As it does so, the plant emits what some describe as a “rotting” odor in order to attract flies and gnats. Certainly not the type of flower you’d like to be bringing home on Valentine’s day!

This early blooming plant is able to withstand the freezing temperatures of early winter through a unique and fascinating adaptation – they can produce their own heat. In fact, it’s not unusual to see the distinctive purple pod of the spathe within a small circle of melted snow, this is because the air within the protective enclosure of the spathe is on average about 20 degrees warmer than the outside air.

The flower covered spadix peeking out of the narrow opening of the spathe. C. Wildflower.org

After the flowering process is complete, the spathe will wither away as the spadix develops dark reddish-purple fruits in place of the flowers. Throughout the spring and summer the seeds will be dispersed in the wet muddy soil. At around the same time the spathe is withering, long leaves begin elegantly unfurling from a single bud at the root of the plant. As each leaf unwinds it reveals a subsequent leaf layer, each leaf can grow up to about 36 inches long.

The lush leaves of skunk cabbage in late spring. C. Wildflower.org

Although Skunk Cabbage in its natural state is poisonous to mammals, it is a food source for some birds, including geese. Most mammals will avoid eating the leaves of this plant because the high calcium oxalate content causes an unpleasant burning sensation in the mouth. However, there are intrepid individuals among us, who have determined that it is possible for humans to harvest and eat the young leaves of the plant. Leaves should be harvested before they have fully unfurled and are at no more than 8 inches of height. The harvested leaves then need to be boiled in four changes of water to properly dissolve the calcium oxalate. Sources report that skunk cabbage prepared in this manner is not unlike wilted spinach in flavor and texture.

Skunk cabbage, if not prepared and harvested in the way described above is poisonous to humans and in large quantities can be fatal. All foragers should rely on multiple sources before heading out to forage on their own, and if possible should seek the guidance of an experienced forager to accompany them.

For more information on preparing skunk cabbage for consumption click here!

Skunk Cabbage Resources






Purple Loosestrife Resources: