Smoky Mountain Poisonous Plants

Smoky Mountain poison hogweed is quite dangerous and should be avoided at all times!

Smoky Mountain Poisonous Plants. Don’t let poison ivy or its relatives scratch your summer fun. “It comes on like a rose, but everybody knows-it’ll really do you in, when you let it get onto your skin” – or so a song goes about poison ivy; and those who come into contact with one of the many plants that contain oils that can cause pure misery will no doubt agree. 

Giant Hogweed looms large on it’s march toward the Smokies. Giant Hogweed can reach up to 20-feet in height and is considered extremely dangerous. It can cause 3rd degree burns and blindness. Typically found in multiple places along the Northeast and Mid-Atlantic regions and now near the Smoky Mountains. Recently Virginia Tech researchers have identified Giant Hogweed in Clarke County Virginia and Wautauga County, North Carolina near the Tennessee line. According to Diane Watwick, Urban Watershed Forester for the Tennessee Department of Agriculture and Forestry, there have been no reported or confirmed sightings of the infamous plant in East Tennessee to date.

Hogweed bears a striking resemblance to Queen Anne’s lace on steroids and is sometimes mistaken for elderberry or cow parsnips-both of which look similar and grow readily in the Smoky Mountain region but rarely exceed 6-feet in height.

Hogweed, whose growth period last from mid May thru July, features huge spiky leaves, which can measure 5-feet in width, and a umbrella-shaped cluster of white flower heads that may exceed 2-5 feet in diameter. According to the USDA Forest Services, USDA and Plant Health Inspection Service, the Giant Hogweed can also be identified by unusual 2-4 inch diameter hollow stems that feature hairy bristles and maroon spots.

Contact with the plant’s clear watery sap can prove disastrous. Symptoms, which can take from 3-5 days to appear, include painful fluid-filled blisters resembling burns, and phytophotodermatitis, which can make skin sensitive to ultraviolet light for years following exposure to Hogweed’s broken stems, roots, flowers, seeds or leaves.

Native to the Caucasus Mountain range in Asia, Hogweed was introduced to other parts of the world through collections in botanical gardens where its escape into other areas proved easy.

The Great Smoky Mountain region, with its miles of wild areas and abundant varieties of vegetation, just might prove the perfect incubator for the monstrous plant which produces some 100,000 seeds annually that are then spread by the wind or running water and can remain viable in the soil for up to 10 years.

Poison oak, poison ivy and poison sumac are three such plants that we all want to avoid.

Poison oak and poison ivy are two plants guaranteed to make life uncomfortable for a few weeks for many people. Both belong to a genus of woody plants in the Anacardiacea family. The name comes from the Greek words for toxic trees. The family includes poison ivy; western poison ivy; eastern poison oak; western poison oak and poison sumac.

Many people have trouble identifying these plants so heed these tips. 

Smoky Mountain poison ivy should be avoided at all times!

Poison ivy has three leaves, one on each side and one in the center. They are shiny with smooth or slightly notched edges. A good general rule for poison ivy is, “Leaves of three let it be!”

Poison oak has a similar appearance, but the leaves are larger and more rounded like an oak leaf. They have a textured hairy surface. When in doubt about either plant, it is safe to go by the old warning, “Leaves of three let them be.”

All these plants contain several different oils but it is the urushiol oil that causes problems. Merely touching the plants will result in transferring urushiol oil to the skin causing an allergic reaction called urushiol-induced dermatitis. Reaction to this is painful and can range from mild to severe depending on the individual’s sensitivity as well as the length of exposure to the plant.

According to a study in the journal, Dermatitis, a close encounter with these particular plants is the most common cause of allergic contact dermatitis in the United States, and the study further states that between 50-75 percent of the population are sensitive to the oils in these plants.

Poison Sumac

While much less common than poison oak or poison ivy, poison sumac, also called thunderwood in the southern regions of our country, is a woody shrub or small tree that thrives in swampy or wet areas as well as piney woods and hardwood regions. It is one of the United States most toxic plants and can cause horrible skin reactions that persist for weeks. A deciduous woody shrub, poison sumac is considered more allergenic than both poison ivy and poison oak all of which release urushiol oil when the plants are bruised or damaged. Any interaction with the oil causes an allergic skin reacting know as contact dermatitis. 

Poison sumac is more related to poison ivy and poison oak that it is to other sumacs. While poison sumac prefers wetlands, most other sumacs are usually found in drier areas with well-drained soils. All parts of a poison sumac are poisonous and the oils remain active even after the plant dies. 

Although winged sumac looks much like poison sumac it is nonallergenic. Winged sumac can be distinguished by its 9-23 leaflets and red berries. Staghorn sumac, another non-poisonous variety, sports bright orange or red berries that grow at the edge of its stems. The leaves of a staghorn sumac have saw-toothed edged, unlike poison sumac. 

How to identify poison sumac. 

Look for reddish stems

Leaves that consist of 7-13 leaflets arranged in pairs with a single leaflet at the end

Elongated leaflets with a smooth velvety texture, smooth edges, and a V-shaped point

Bright orange leaves in the early sprig that turns green and glossy and then turns red-orange in the fall

Small, yellow-green clusters of flowers

Ivory-white or gray loosely-packed fruit.

Symptoms of contact with any of these plants can appear from 8-48 hours after exposure and include:


Burning sensation on the skin



Watery blisters.

What do if you come into contact with any of these plants? 

The Center for Disease Control and Prevention recommends rinsing with rubbing alcohol and washing with specialized poison plant wash or degreasing soap (such as dishwashing soap) and lots of cool water- hot water may cause the oil to spread. Take particular care not to get the oil in your eyes.

You should also wash any items that have touched the plant.

Time is the only cure for the aggravating rash. However, there are several over-the-counter remedies that can help soothe your symptoms.

These include;

Calamine lotion

Hydrocortisone creams

Topical anesthetics, such as menthes or benzocaine

Oral antihistamines, such as Benadryl

Oatmeal baths may also help relieve itching.

Your doctor may prescribe oral or topical steroids to reduce inflammation


If the rash spreads over a large portion of your body (30-50 percent.) 

If your rash becomes infected due to scratching.  

Your reaction is severe or widespread

You inhaled the smoke from a burning poison sumac, oak or ivy and have difficulty breathing

Your skin continues to swell

The rash affects your eyes, mouth or genitals

Blisters are oozing pus

You develop a fever greater than 100 F (37.8C)

The rash does not improve within a few weeks.


Although some reactions can heal quickly once the irritant is removed some may linger for as long as 3-4 weeks and, in extreme cases, can cause permanent scarring. This generally happens with people who experience severe reactions and tend to scratch their skin which causes open sores and lengthens the healing time.

Be aware that urushiol oil can also contaminate other common objects such as:



Walking sticks

Gardening tools


A person or pet with this oil on their skin can pass it along to another person who touches the affected skin.

A word of caution, never burn poison ivy, poison oak or poison sumac in an effort to eradicate it. Smoke from any of these plants can cause severe lung damage.

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