Plant That Can Cause Permanent Blindness Found Growing in Midwest

Bare-skin contact with sap-covered parts of the plant can cause painful blistering, long-lasting scars and blindness

A highly dangerous plant whose sap can cause permanent blindness was found growing in Calhoun County in southern Michigan.

The plant, known as giant hogweed, was found in Pennfield Township near Battle Creek. The Calhoun County Public Health Department issued a press release Monday warning anyone in the area of the dangers of the plant and cautioning them to be on the lookout for more of it.

Giant hogweed is a weed that is not commonly found. When it comes in contact with bare skin, however, it can be highly noxious, according to the public health department.

Bare-skin contact with sap-covered leaves, roots, flower heads, seeds and hairs on the stem can cause painful blistering and long-lasting scars. If the sap gets in a person's eyes, it can cause permanent blindness. The harm may not be immediately noticeable as it can take up to 48 hours for the reaction to happen.

Hogweed sap is activated by sunlight, so protecting exposed skin from sunlight for several days can help reduce blistering. Flushing the eyes with water immediately after exposure can also lower the risk of permanent blindness.

Health department officials plan to monitor the site where the giant hogweed was found for the next several years in case new growth is discovered. Meanwhile, the existing plant has been removed.

Although only one plant was found, weed experts say it can become an invasive species. Large colonies can grow from a single plant's seeds, and it can take up to five years to completely eliminate a colony, according to Michigan's Department of Agriculture and Rural Development.

The health department warns anyone in Calhoun County to be on the lookout for the plant, which can easily be confused with harmless Queen Anne's lace or cow parsnip.

Giant hogweed is characterized by dark red or purple spots and bristles on the green stem. White flower heads also grow on the plant and can produce thousands of seeds. Green leaves at the base of the plant can grow to five feet in diameter, and the plant can grow up to 18 feet tall.

The weed flowers from late spring to mid-summer and only appears every other year.

Health department officials ask anyone who spots suspected giant hogweed to report it to the department and submit a photo of the plant for identification to pestid@msu.edu.

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