Summertime in Waldo County means being outside more. Most wild plants are not harmful, or are only toxic if ingested, but even a quick brush with the sap of some plants growing in Waldo County can cause painful rashes, according to those who study them.

The toxicity of abundant native plants like poison ivy, poison oak and poison sumac is common knowledge, but non-native plants like giant hogweed and wild parsnip pose a threat that many Mainers are unaware of. Neither is native to Maine; however, state horticulturist Gary Fish does not consider either of them to be invasive at this time.

Both are members of the carrot family that come from the mountains of Eurasia, and giant hogweed is the bigger concern — and the more toxic — of the two. Wild parsnip has been reported online and by word of mouth in Winterport, Frankfort, Belfast, Searsmont and Unity. Giant hogweed has no public reports online right now, but Fish said he knows it is growing along the Kenduskeag River in Bangor.

Wild parsnip has a flower that looks like yellow Queen Anne’s lace. Source: maine.gov

Injury to humans comes not from the plants themselves, but from their sap. Skin contact with this sap, by cutting or breaking a plant, can produce a rash called phytophotodermatitis. Fish explained that when a person’s skin comes into contact with chemicals in the sap called furocoumarins and then is exposed to the ultraviolet light of the sun, the skin becomes inflamed. This also causes an itching, burning feeling, and pigmentation deep within the skin — similar to the effects of a sunburn, but much longer-lasting, and worsening with further sun exposure. Hogweed, parsnip and other members of the carrot family can cause such a reaction, but so can citrus fruits and parsley, Fish said.

University of Maine Cooperative Extension Prof. Rick Kersbergen said the best way to prevent injury is to avoid the plants altogether. Hikers can protect themselves by making sure not to break plants if they have to get close to them and wearing long sleeves and pants. Rashes take sun exposure to develop, so it may be several days before they appear on skin; self-monitoring is important for those who have been around the plants.

Steve Byers, who owns Back Country Flora LLC in Waldo, offered an herbalist’s perspective on the plants. He grows wild parsnip for consumption — even though their sap is harmful to the skin, the parsnips themselves are perfectly edible, he said. To treat rashes, his recommended “general natural approach” is to apply aloe juice, lavender oil and/or vitamin E to affected areas.

To eradicate either of the plants, Byers says it is best to do so in their first year of life. Choose a cool, cloudy day to dig up plants. “(The rash’s phototoxins) need sunlight and sweat to be activated,” Byers said, and it is recommended to wear gloves, long sleeves and eye protection when handling plants. He also stressed that it is not like a poison ivy reaction — phytophotodermatitis lasts longer and is more serious.

The history of these plants is also notable — and Fish is very knowledgeable when it comes to plant history. Though non-native (and with the potential to be invasive), wild parsnip and giant hogweed were brought to the United States intentionally. Wild parsnip, as mentioned above, is edible. It is found throughout the United States, and “was brought over by European settlers, probably as far back as the 1600s,” said Fish. Giant hogweed was a “prized oddity” for rich estate owners on the coast. Popular in the late 1800s and early 1900s, hogweed is now found in both Canada and the United States, from British Columbia, Washington and Oregon to Newfoundland, Ontario and Wisconsin and south to Indiana, Maryland and New Jersey, according to Fish. Both are prevalent throughout New England.

To report either of these plants on your property, email Fish at horticulture@maine.gov. You can also report them online for public purposes. Fish recommended the websites iMapInvasives and iNaturalist.

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