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An Invasive Weed That Burns and Blinds People Is Spreading Across the Country — Here’s How to Spot It

Virigina officials are warning residents to avoid giant hogweed, an invasive plant that can cause third-degree burns and blindness, after it was recently spotted in the wild. Almost a dozen other states have reported giant hogweed sightings, and it’s possible that the list will grow. With warm weather on the way, you and your family will no doubt be spending more time outside. Here’s how to keep your loved ones safe.

How to Identify Giant Hogweed

Giant hogweeds are recognizable by their umbrella-shaped clusters of 50 to 150 white flowers. When they’re flowering, hogweeds can stand between eight and 15 feet tall. Their stems can grow between two to four inches in diameter, and they have purple splotches on them. Hogweed leaves are large, reaching at least five feet across; the undersides of the leaves are covered in stiff, dense hairs.

Pictures of Giant Hogweed

Giant Hogweed

(Photo Credit: Getty Images) 

Hogweeds can be considered perennials, though they sometimes die after blooming. The plant’s winged seeds travel in water, through soil, or are moved by animals; their seeds are hardy and can still grow after 10 years in the soil. Flowers grow from mid-May to July, with seeds forming toward the end of that growth window.

Giant Hogweed Stems

Giant hogweed stems. (Photo Credit: Courtesy of 

These plants are considered public health hazards because they can cause serious harm to not only humans but also to local ecology. Hogweeds aren’t used for either food or shelter by most animals; they also push out other helpful plant species with their aggressive growth.

Giant Hogweed Leaves

(Photo Credit: Courtesy of 

Where is giant hogweed found?

Giant hogweed grows in New England, the Northwest, and the Mid-Atlantic regions of the United States. You can see which states recorded giant hogweed growth in the 2014 map below. The invasive species has spread since this map was released.

Giant Hogweed Burns

The sap of a giant hogweed can cause phytophotodermatitis, meaning your skin becomes super sensitive to sunlight. As a result, you may experience painful blisters that can become dark in color and scar for as long as six years (though most of the time they disappear after a few months). If you get sap in your eyes, you could also go blind. Skin sensitivity can last for years after initial contact with hogweed.

What to Do If You Come in Contact With Giant Hogweed

New York State’s Department of Environmental Conservation advises washing the affected area with soap and cold water as soon as possible, and keeping it away from the sun for 48 hours. If you develop a rash after touching giant hogweed, you can apply a topical steroid cream to reduce your discomfort. See a doctor immediately if you think you have a giant hogweed burn.

Giant Hogweed vs. Cow Parsnip and Other Hogweed Lookalikes

To make matters worse, giant hogweed has a lot of lookalikes. So what’s the difference between giant hogweed versus cow parsnip and other similar-looking plants?

Giant Hogweed vs. Cow Parsnip 

Leaves: Giant hogweed leaves are larger (about five feet wide), while cow parsnip leaves are only about two to two-and-a-half-feet across. Cow parsnip leaves are also less incised.

Flowers: Giant hogweed flowers are umbrella shaped, while cow parnsip are flat-topped. Size again is another differentiating factor, with clusters of giant hogweed blossoms stretching up to two-and-a-half-feet wide. Clusters of cow parsnip flowers are no bigger than a foot wide.

Stem: Both plants have stems with furry white hairs, but giant hogweed stems have purplish-red splotches and cow parsnip stems are completely green.

Flower Ray: Think of a flower ray as an individual stem in a cluster. For giant hogweeds, flower rays number 50 or more, while for cow parsnips, that number is only 15 to 30 flower rays per cluster.

Giant Hogweed vs. Regular Parsnip 

Leaves: Regular parnsnip leaves are made of five to 15 little ridged leaflets — a totally different shape from those of a giant hogweed.

Flowers: Regular parsnip flowers shoot off a single stalk and are yellow.

Stem: Regular parnsip stems are yellowish-green in color and do not have hairs.

Giant Hogweed vs. Queen Anne’s Lace 

Leaves: The leaves of a Queen Anne’s lace are smaller, thinner, and more fern-like than those of a giant hogweed.

Flowers: Queen Anne’s lace flowers are tiny clusters only three to four inches wide.

Stem: Both stems of giant hogweeds and Queen Anne’s lace are hairy, but the latter is hollow and green.

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