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Caught red handed: poison parsnip

July 27, 2010
Adirondack Daily Enterprise

Have you seen a plant along the roadside about 4 feet in height with an airy flower that looks like Queen Anne's Lace but is bigger and, instead of being white, it is yellow?

If so, you may be seeing wild parsnip (Pastinaca sativa), also known as poison parsnip. Alerts from landowners concerned about this plant keep coming in. Stories of rashes, burns, and other skin irritations evoke images of a torture scene. Can a plant do that? Yes, and unfortunately each year wild parsnip seems to be gaining in numbers and expanding its distribution.

Because of the severe allergic reaction from brushing against the plant, people call us thinking they came into contact with another invasive plant we warn about - giant hogweed (Heracleum mantegazzianum). Both plants cause blistering, but the distinguishing feature of wild parsnip is its yellow flowers in flat-topped, umbrella-like clusters called umbels (unlike giant hogweed which grows to 15 feet in height and has a large, white, umbel-shaped flower).

Article Photos

Poison parsnip leaves
(Photo— Hilary Smith)

Chemicals in the leaves, stems, and fruits of wild parsnip cause phytophotodermatitis to the skin by reducing the skin's ability to protect itself from ultraviolet light. A rash, blistering or skin discoloration can occur and scarring can last from days to months and even up to a year.

Wild parsnip was introduced from Europe in the 1600s. It is intolerant of shade and invades disturbed settings, such as roadsides and waste areas, and fields, wet meadows and agricultural lands. Like other members of the carrot family, wild parsnip is anchored in place by a long, thick taproot. It grows first as a rosette of leaves fairly close to the ground, and, in its second summer, the plant sends up a single flower stalk that reaches heights greater than 4 feet that has hundreds of yellow flowers. Compound leaves grow alternately on the main stem which is hairless and has vertical grooves. Leaves have two to five pairs of oppositely arranged, sharply toothed leaflets.

Look for the large, yellow flowers June through July. Plants slowly invade an area in waves following initial infestation. Once the population builds, it spreads rapidly by seeds, which are fairly large and produced in abundance. The recent explosion of wild parsnip may be due to birds and small mammals, which eat the seeds, and also to roadside mowing regimes, which may permit the plants to produce ripe seeds well before any mowing is done.

Also, when roadsides and pastures are mowed in late July and August, parsnip seeds probably move as hitchhikers on the mowers. Relatively mild winters may enhance survival of seeds that germinate and become established in the fall.

Care should be taken to avoid skin contact with the juices of this plant. Proper clothing (gloves, a long-sleeved shirt and long pants) must be worn to prevent the phytophotodermatitic effects. Control the plant by digging or cutting the root below ground level. In some soils, the plants can be pulled. Plants may resprout when cut above the ground, and should be cut again a few weeks later to prevent flowering. All plant material and seeds must be bagged, removed from the site and disposed of in a landfill or by burning.

If you suspect you have wild parsnip in your yard, the first thing you should do is make a positive identification. If accidental exposure to the plant sap occurs, wash the affected area thoroughly with soap and cold water as soon as possible. Protect the exposed area from sunlight for at least 48 hours. If you have a reaction, see a physician.


Eye on Invasives is a biweekly column that spotlights a top invader when it is easiest to identify. Hilary Smith directs the Adirondack Park Invasive Plant Program, a partnership program housed at the Adirondack Chapter of The Nature Conservancy in Keene Valley, NY. Find out more about this award-winning program online at HYPERLINK ""



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