What is wild parsnip?

Wild parsnip identification is worth learning before you start clearing an overgrown field edge or roadside bank. It’s a biennial in the carrot family from Europe and Asia, the wild form of the garden parsnip, and its sap can cause serious, sun-activated burns on bare skin.

The PA Department of Agriculture lists it as a Class B noxious weed. It has spread along highways, back roads and field edges across Pennsylvania, and mowing of roadsides at the wrong time has helped carry its seed even farther.

Wild parsnip identification: what to look for

• First year: a low rosette of compound leaves that stays under a foot tall. Leaves have 2 to 5 pairs of oval, sharply toothed leaflets along a central stalk. The plant can sit as a rosette for more than one year.
• Flowering year: in spring the plant bolts, sending up a stout, grooved stem 2 to 5 feet tall. The stem is hollow except at the joints.
• Flowers: flat-topped clusters of small yellow flowers, 4 to 8 inches across, shaped like an umbrella. In Pennsylvania they bloom from June into early August.
• Seeds: flat, oval and papery, about a quarter inch long, ripening in late summer. After seeding the plant dies, but the dry stalks stand into winter.
• Root: a thick, pale taproot that smells like parsnip.

Where it grows in Pennsylvania

Wild parsnip loves sun and disturbed ground. It’s most common along roadsides and highway medians, railroad grades, old fields, pastures, trail edges and unmowed banks. It handles a wide range of soils.

In yards, it typically moves in along the road frontage, back field edges or a bank that only gets mowed once or twice a year. Kids and pets playing in tall grass and anyone running a string trimmer are most at risk of burns.

Burns often happen in midsummer when people are out cutting brush in shorts and short sleeves. The rash shows up a day or two later, so it’s easy not to connect it to the plant. Streaky or drip-shaped burns on the arms or legs are a classic sign.

Wild parsnip look-alikes

• Golden alexanders is a native wildflower with yellow umbels too, but it blooms earlier in spring, has smooth, often purplish stems, fewer leaflets and smaller, tighter flower clusters. It’s worth keeping.
• Poison hemlock has white flowers, finely cut fern-like leaves and smooth stems with purple blotches. It’s extremely poisonous to eat.
• Queen Anne’s lace has white, lacy flower heads, carrot-like leaves and hairy stems.

How to get rid of wild parsnip

Always gear up first: gloves, long sleeves, long pants and eye protection. Working on a cloudy day or late in the day lowers the risk of a burn if sap does touch your skin.

Hand and mechanical:

• For small patches, cut the root an inch or two below the soil with a sharp spade and lift the plant out. This works on rosettes and on flowering plants before seed.
• Cut flowering stalks in early summer, after flowers open but before seeds ripen, and bag the flowering tops.
• Don’t mow or string-trim plants that have already gone to seed, which spreads the seed. Avoid trimming any time with bare skin exposed.
• Expect to repeat for a few years until the seed bank is used up.
• Leave pulled plants in a sealed bag in the trash, not in a brush pile where kids or pets could brush against them.

Cultural: wild parsnip struggles in thick, established grass. After removing it, seed bare ground with a competitive grass mix and keep it mowed regularly, which prevents rosettes from ever flowering.

Herbicides: rosettes are the best target, and they can be treated from spring through fall, ideally before flowering. Extension guidance for roadsides lists selective broadleaf products, including products containing 2,4-D, triclopyr or metsulfuron, as well as glyphosate, which kills grass too. Multiple years of treatment are usually needed. Read and follow the product label every time; the label is the law. Check that the product is labeled for your site, whether that’s a lawn, a landscape bed, woods, a roadside or ground near water, where only aquatic-labeled products belong. Applying herbicide for hire in Pennsylvania requires a PA Department of Agriculture pesticide applicator certification, so bigger jobs belong with a licensed lawn-care or vegetation-management company.

Keeping it from coming back

Seeds can stay alive in the soil for several years, so check road frontage and field edges every spring for rosettes. Keep regularly mowed lawn between the roadside and areas where kids and pets play.

Clean mowers and trimmers after cutting near wild parsnip, both to avoid spreading seed and so you don’t get sap on your hands later. Share what you know with neighbors, since many people don’t realize what caused their burns until they see the plant again.

If a large roadside stand borders your property, the township or PennDOT may manage the right-of-way itself. A quick call to find out who maintains that strip can save you from tackling it yourself.

Questions we get about wild parsnip

Similar weeds

Giant HogweedHeracleum mantegazzianumPoison HemlockConium maculatumQueen Anne's Lace (Wild Carrot)Daucus carota