Wild parsnip (Pastinaca sativa)

Synonyms: Pastinaca sativa subsp. sylvestris, Peucedanum sativum

Common Names: Common parsnip, poison parsnip, wild parsnip weed

Description:

Wild parsnip (Pastinaca sativa) is a tall plant in the carrot family, native to Europe and Asia, that escaped from gardens and now grows wild across most of the United States [1][2]. It is the same species as the garden parsnip, but the wild form is best known for its sap, which can cause severe skin burns in sunlight [2]. MISIN tracks it because it spreads quickly along roadsides and into fields and prairies, and because it is a real hazard to people, pets, and livestock [2].

Habit:

Wild parsnip lives for two years. In its first year it grows as a low rosette (a flat ring of leaves at ground level), with compound leaves made of several toothed leaflets that look much like celery or garden parsnip leaves [2][4]. In its second year it sends up a hollow, grooved flower stalk 3 to 6 feet tall, topped with broad, flat-topped clusters of small yellow flowers [2][4]. The yellow umbrella-shaped flower clusters are the giveaway ? few other tall weeds in open ground have flat yellow flower heads [2].

The easiest time to spot wild parsnip is June and July, when it is in full yellow bloom and stands above the surrounding grass [2]. The dried brown stalks and seed heads stay standing into fall and winter, which also helps you find old patches to clean up [2]. Do not touch the plant with bare skin ? its sap can burn (see Ecological Impact) [2].

At-a-glance cues:

1. Broad, flat-topped clusters of small yellow flowers in early summer [2]
2. Hollow, grooved flower stalk 3 to 6 feet tall in the second year [2][4]
3. Compound leaves with 5 to 15 toothed leaflets, like a large celery leaf [2]
4. First-year plants are a flat rosette of leaves at ground level [2][4]

Leaves:

1. Arrangement: alternate along the stem; first-year plants form a flat rosette at ground level [2][4]
2. Shape: pinnately compound (one leaf made of many leaflets along a central stalk), with 5 to 15 leaflets [2]
3. Margin: leaflets are coarsely toothed and often have mitten-like lobes [4]
4. Surface: yellowish-green and mostly smooth (not hairy) [2][5]
5. Size: the whole leaf can be up to about 16 inches long [2]

Stems:

1. Habit: an upright, herbaceous biennial (occasionally taking a third or fourth year to flower) [2]
2. Height: the second-year flower stalk reaches about 3 to 6 feet [2]
3. Cross-section: stout, hollow, and grooved or ridged [2][4]
4. Surface: green and mostly hairless [5]
5. Root: a long, light-colored taproot, much like a garden parsnip [2]

Flowers:

1. Color: small and yellow, each with five petals [2]
2. Arrangement: in flat-topped umbrella-shaped clusters (umbels) 2 to 6 inches wide [2]
3. Bloom time: late spring through midsummer, mainly June and July [2]
4. Sex: flowers are perfect (each has both male and female parts) [2]

Fruit and seeds:

1. Type: small, flat, rounded, slightly winged seeds (held in pairs that split apart) [2]
2. Color: straw-brown when ripe [2]
3. Ripening: late summer; the seeds stay on the dried stalks into fall and winter [2]
4. Dispersal: carried by wind, water, animals, mowing, and on clothing, equipment, and vehicle tires [2][5]
5. Output: a single plant produces many seeds, which remain able to sprout in the soil for several years [5]

Habitat:

Wild parsnip is native to Europe and Asia and was brought to North America as a root vegetable; it now grows wild across most of the United States [1][2]. It is a plant of open, sunny ground [2].

It is most common along roadsides, in old fields and pastures, in prairies and savannas, and on trail edges and other disturbed ground [5]. It needs sun and spreads fastest where the soil has been disturbed, but it can move from roadsides into nearby natural areas [2][5].

Reproduction:

Wild parsnip spreads only by seed, and the seeds move easily onto and across a property [2]. They blow in on the wind, wash along ditches, hitch a ride on clothing, mowers, and tires, and are scattered when roadsides are mowed while the seeds are ripe [2][5]. New plants often show up first along a driveway, fence line, or field edge [5].

A seed sprouts in spring and spends its first year as a low rosette of leaves [2]. In the second year the plant bolts, flowers in June and July, sets seed by late summer, and then dies [2]. Because the seeds can stay alive in the soil for several years, controlling a patch takes repeated effort, and the key is to remove plants before they set seed in mid summer [5].

Impact and Damage:

The biggest concern with wild parsnip is human health. Its sap contains natural chemicals (furanocoumarins) that make skin extremely sensitive to sunlight [2]. When sap from a brushed or broken plant gets on bare skin and that skin is then exposed to sunlight, it can cause a painful chemical burn with redness, swelling, and blisters within a day or two ? not an allergy, but a true burn [2]. The burned skin can stay discolored and sun-sensitive for up to two years [2]. The same chemicals harm animals: horses and other livestock that eat wild parsnip in hay or pasture can develop serious skin and eye damage [3].

In natural areas, wild parsnip forms dense stands in prairies, savannas, fields, and roadsides, crowding out native grasses and wildflowers and lowering the variety of plants an area supports [5]. Because it makes large amounts of long-lived seed and spreads readily along mowed roadsides, it can build up quickly and is difficult to remove once established [2][5].

Similar species:

Several carrot-family plants with umbrella-shaped flower clusters are mistaken for wild parsnip.

Golden alexanders (Zizia aurea) is a native plant with similar flat-topped yellow flower clusters, but it is much shorter and blooms earlier, and its leaves are divided into only three to seven leaflets rather than the long, many-leafleted leaves of wild parsnip [5].

Prairie parsnip (Polytaenia nuttallii) is a native look-alike with yellowish flowers, but its leaflets are more oblong with few teeth and its flower clusters are more rounded than the broad flat heads of wild parsnip [5].

Wild carrot (Daucus carota), also called Queen Anne's lace, has the same umbrella-shaped flower clusters and grows in the same open places, but its flowers are white rather than yellow and its stems and leaves are hairy [5].

Cow parsnip (Heracleum maximum) is a much larger native plant with similar umbrella-shaped clusters, but its flowers are white and its big leaves are hairy underneath, unlike the yellow flowers and smooth leaves of wild parsnip [5].

Monitoring and rapid response:

Signs to watch for:

1. Broad, flat-topped clusters of small yellow flowers on tall stalks in June and July, especially along roadsides, fields, and trail edges [2][5]
2. Flat rosettes of celery-like, toothed leaves at ground level in the first year [2][4]
3. Dried brown stalks and seed heads standing into fall and winter [2]

What you can do:

1. Always wear gloves, long sleeves, long pants, and eye protection ? the sap can burn skin in sunlight, so cover up and work on cloudy days or in the evening when you can [2].
2. For a few plants, dig or cut the taproot about 1 to 2 inches below the soil surface before the plant sets seed; this kills the plant [2].
3. If plants are already flowering or seeding, carefully cut off and bag the flower and seed heads first so you do not scatter seed, then remove the rest of the plant [2].
4. Bag pulled plants and seed heads for the trash, and wash your skin, tools, and clothing thoroughly afterward; stay out of the sun for several hours after any skin contact [2].
5. Natural area crews can mow or cut large stands just before flowering, and return over several years to dig or cut resprouts and new rosettes, working outward from the edges and clearing small outlying patches first [5].

When to call a professional:

1. Large or well-established stands, or plants along busy roadsides and rights-of-way where safe hand removal is not practical [5]
2. Any situation where you cannot safely avoid skin contact with the sap [2]
3. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. USDA NRCS Plants Database. Pastinaca sativa L. plants.usda.gov
2. Utah State University Extension. Wild Parsnip (Pastinaca sativa) Identification and Control in Residential Landscapes. extension.usu.edu
3. Winter JC, Thieme K, Eule JC, Saliu E-M, Kershaw O, Gehlen H (2022). "Photodermatitis and ocular changes in nine horses after ingestion of wild parsnip (Pastinaca sativa)." BMC Veterinary Research 18:84. pmc.ncbi.nlm.nih.gov
4. Michigan State University Extension, Plant & Pest Diagnostics. Wild Parsnip - Pastinaca sativa. canr.msu.edu
5. Wisconsin Department of Natural Resources. Wild parsnip (Pastinaca sativa). dnr.wisconsin.gov

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