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Beware of Toxic Carrots

The carrot family, which boasts a variety of familiar edibles such as parsley, celery, carrots, anise, fennel, and cilantro, also contains two highly poisonous plants that many people confuse for their nontoxic counterparts. 

Martin Quigley, an Ohio State University assistant professor of landscape ecology, says people should learn to recognize poison hemlock and wild parsnip. These plants look similar to and smell like other plants in the carrot family (Apiaceae, formerly known as Umbelliferae). Both plants originated in Europe, but are now commonly found in America, growing in wet, wooded areas and open fields, and along roadsides and railroad tracks. 

Poison Hemlock Poison hemlock, which has nothing to do with the evergreen hemlock tree, is very hard to distinguish from other family members,” says Quigley. “It’s earned the nickname fool’s parsley. Because the leaves smell and look just like those of a large wild carrot there have been cases of adults, children and farm animals accidentally being poisoned by eating just a leaf or two.”

Poison hemlock, most famous as the plant that was used to execute the Greek philosopher Socrates, can be fatal if ingested. The plant was used through the 19th century as a narcotic and an anticoagulant and to treat inflammatory diseases, but was discontinued because of the uncertainty of dosage required. Coniine, the active ingredient in the plant, is also a poison that causes paralysis of the muscles,  including those used for breathing. There is no known antidote.
Poison hemlock is the most toxic indigenous plant in North America. Reports of hemlock poisoning are rare, but it has happened. The Center for Disease Control reports that from 1979 to 1988 at least 58 people died after ingesting a poisonous plant that was misidentified as an edible fruit or vegetable. Five of those deaths were caused by poison hemlock. 

Quigley says the main feature that distinguishes poison hemlock from other carrot family members is its tall size. “It’s the tallest of the carrot family, growing to more than six feet in moist conditions,” he sys. Wild parsnip also looks similar to other carrot family members. The plant is relatively harmless if ingested, but causes severe burns if the juice of the plant comes into contact with the skin.

“The plant is highly phytophototoxic, meaning that the juice only reacts with the skin when sunlight hits it,” says Quigley, showing his scarred arm as evidence. “I  wore a T-shirt while leading a wildflower walk, and broke some stems without even realizing it. There is no recognized treatment, but one way to reduce the rash is to use athlete’s foot ointment to try to dry it up.

Deep golden yellow flowers, which are present on the plant through July, distinguish wild parsnip from its lighter yellow-flowering family members. Plants in the carrot family are easily recognized by their fern-like leaves and the prominent white or yellow flat-topped cluster of flowers that grows in an umbrella-like position.

Ignorance, Quigley says, is the biggest reason why people confuse poisonous plants with harmless ones.

“People are always out in the woods hunting for edible plants. But our society is largely urban now. When most Americans were farmers, everyone knew what to look out for. Now, most people don’t know the difference between good plants and those that can be dangerous.”

Quigley says the best recommendation when dealing with wild plants is to avoid them altogether. “Don’t pick or attempt to eat anything if you are not absolutely certain you know what it is,” he said.

Ohio State University Extension

Toxic Plants of North America
Covers toxic plants -- both wild and planted -- found on the North American continent north of the Tropic of Cancer. Covers both animal and human intoxications with pertinent information, including:
  • Plant morphology and distribution
  • Associated disease problems
  • Toxicants and their mechanisms of action
  • Clinical signs and pathological changes of intoxications
  • Treatment approaches
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