Giant Hogweed Plant
Written By Jeffrey Roth
They are here, and some of them are out to get you.
From microscopic to macroscopic, invasive species can be beneficial, annoying, destructive and even dangerous to humans and the ecosystem.
A native of the Caucasus region that was once considered just a large, decorative plant, Heracleum mantegazzianum, or the giant hogweed plant, can grow to 15 feet high and is more of a beast than a beauty. Physical contact with the plant can cause serious injuries, and it has been found in Pennsylvania, the D.C. area, and in a number of Maryland counties.
First found in Maryland in 2003, the giant hogweed exudes a clear, watery sap that causes one’s skin to become photosensitive to ultraviolet radiation. Contact with the sap can cause severe burns, blisters, dermatitis, permanent scarring, temporary blindness, and may result in future medical complications, such as skin cancer, according to the Maryland Department of Agriculture.
It is illegal to sell or move giant hogweed plants or seeds across state lines. Seeds, however, eaten by birds or animals, can be dispersed through droppings. Jonathan McKnight, associate wildlife director of the Maryland Department of Natural Resources, said that although giant hogweed plants have been found in Maryland, they are not common and are easy to eradicate.
Fire ants and Africanized bees are two invasive species of insect that have appeared in Southern Maryland. Fire ants were introduced from South America. The bees, sometimes called “killer bees,” are a hybrid of European and African honeybees. Human contact with both species of insects can result in serious, painful injuries, said McKnight.
Another non-native insect that causes economic problems and has become a nuisance is the ubiquitous stink bug, originally a native of Asia.
“In general, invasive species come from all forms of life,” said McKnight. “From my point of view, the small ones are the scary ones. The big ones are more obvious, but it is the little ones that really get you.”
McKnight said diseases such as Dutch elm, chestnut blight and sudden oak death, can spread quickly and kill specific tree species. Attempts at the containment of various plant pathogen outbreaks usually require the destruction of infected plants.
Nutria, semi-aquatic rodents that were originally imported from South America to the United States for their fur, were first spotted in the Chesapeake Bay area of Maryland about 70 years ago, McKnight said.
The herbivore feeds on wetland plants and causes serious habitat problems.
Northern snakehead fish, native to China, caused a stir in Maryland when they were discovered in a Crofton pond 10 years ago. They are believed to have been introduced in domestic waters by careless collectors.
Characterized by National Geographic as “Fishzilla,” the fish have no natural enemies, decimate local fish populations, and can actually breathe for a time outside of the water. Snakeheads have been caught in the Little Hunting Creek and the Potomac River.
Zebra mussels, originally native to Southeast Russia, disrupt ecosystems, damage harbors, waterways, ships and water treatment and power plants. They first appeared in Maryland two years ago.
Rock snot, a slimy, non-native algae that has been known to contaminate fish hatcheries, has also been discovered in Maryland. It is believed to have been introduced in the U.S. from Europe, carried on contaminated fishing and wading gear.
A relative newcomer, the rusty crayfish, native to the Ohio River Valley, is causing concern in Maryland.
The emerald ash borer, native to Asia, is a destructive insect that is on the state’s watch list. A green beetle, it is highly destructive to ash trees, and causes more damage than chestnut blight and Dutch elm disease. In response, many states have launched educational advertisement campaigns urging the public not to transport firewood from one state to another, since that is one way the borer is introduced to new areas.
Non-native species have been invading North America since the first European explorers set foot on the continent. Inadvertently, the first ships brought black rats to the New World in the 16th century, and Norway rats were first reported on the East Coast of the United States in 1775. Ironically, black rats were introduced to Europe from Asia as early as the second century BCE; while Norway rats traveled with returning Christian armies from the Holy Lands during the Crusades.
The first colonists introduced wheat, rice, soybeans, domesticated fowl, cattle and horses, to name but a few of the non-native species that were intentionally imported to American shores.
Unfortunately for native Americans, the colonists also brought non-native diseases, such as the smallpox virus, to which indigenous people had no immunity, said McKnight.
As global travel increased over the past several centuries, the number of invasive species brought to this country, both by design and accident, has increased exponentially. Quite often, the introduction of what were thought to be beneficial non-native species has had unforeseen repercussions.
The gypsy moth was imported to Medford, Mass., in 1869 by Leopold Trouvelot, as a silk-producing business venture. Unfortunately, caterpillars escaped from his backyard facility. By the early 1900s, the voracious insects began defoliating hardwood forests throughout New England and the mid-Atlantic region of the country, including Pennsylvania and Maryland.
Starlings and house sparrows are ubiquitous in this area, but they are actually non-native birds. Blame Shakespeare for their introduction to the States, said Brett A. McMillan, a professor of biology at McDaniel College and a member of the Maryland Native Plant Society.
In the 19th century, a group of American Shakespeare fans decided to import every bird mentioned in the plays of the Bard of Avon.
A Bronx, N.Y., pharmaceutical manufacturer, Eugene Schieffelin, and the American Acclimatization Society released hundreds of starlings in New York’s Central Park. Since then, they have established themselves firmly throughout the country and are generally considered a nuisance. The bluebird population has suffered as a result, said McMillan.
Marc Imlay, conservation biologist, park ranger and non-native invasive plant control coordinator for the Maryland-National Capital Park and Planning Commission and chair of the habitat stewardship committee of the Maryland Chapter of the Sierra Club, said volunteers have spent hours working to remove various invasive plant species from the Patuxent River Park, near Upper Marlboro.
Invasive plant species are divided into three different classes based on their impact on endangered species.
“At most of our sites we removed class 1, 2 and 3 species,” Imlay said. “This spring at all of our parks, we removed Japanese honeysuckle, a Class 1 species, when we discovered it climbing a tree.
“During winter, we remove periwinkle and English ivy, which are Class 2 species, and Chinese wisteria, a Class 3 species. Where we don’t have the ability to remove all three classes, we focus on the first two, such as Japanese stiltgrass.”
Burning bush plants, popular with homeowners for their fiery red color, can be easily purchased in the area. The problem is that their seeds are easily spread and they can crowd out native species.
The porcelain-berry is a deciduous woody perennial that twines and climbs. Much like English ivy, it can quickly take over an area, becoming a nuisance.
In workshops, Imlay teaches students methods of eradicating non-native plant species including physical removal, herbicides and biological controls. Historically speaking, the results of introducing a non-native biological control for invasive-species has had varying success.
Using an Asian weevil, Rhinoncomimus latipes to control the weed known as the mile-a-minute vine, a native of China, has proven effective, Imlay said. The weed is so named, because it can grow up to six inches in a day. The weevil feeds on the vine and not on any other plants.
In 2004, the U.S. Department of Agriculture approved the sale of the weevil for control of the mile-a-minute vine, Imlay said.
Steven Allgeier, master gardener coordinator for the Carroll County Cooperative Extension Service, Westminster, said two insect species that originally were considered beneficial non-native species, such as the European nightcrawler and the Asian lady beetle, have demonstrated an adverse impact on the ecosystem.
The nightcrawlers actually decrease the depth of the forest floor. During the winter, said Allgeier, the Asian lady beetle hibernates at higher elevations. As a result, they can infest houses and the engines of chainsaws and snowblowers, causing them to overheat.
Carolyn Puckett, master gardener of Carroll County and a member of the Maryland Invasive-species Council, said she “heads up the Carroll County Weed Warriors,” volunteers who in 2010 removed invasive plant species at the Hashawha Environmental Center and the Bear Branch Nature Center in Carroll County. In 2011, they extended their efforts to the Piney Run Nature Center in Sykesville, and Charlotte’s Quest Nature Center in Manchester.
Recently, Puckett led a training session on invasive species for the Audrey Carroll Audubon Sanctuary in Mt. Airy.
Residents can help prevent the spread of non-native plant species by simply not buying and planting them on their properties, Puckett said.
