Wild Parsnip (Pastinaca sativa) is an invasive plant species that has spread widely across North America. The term “poison parsnip” refers to this wild escapee, which poses a health risk due to a toxic sap found in its stems, leaves, and flowers. Contact with the plant’s sap, followed by sun exposure, triggers a severe chemical burn known as phytophotodermatitis. Understanding the plant’s distinctive features is the first step in avoiding this painful reaction and preventing its spread.
Key Features for Identification
The most distinguishing characteristic of Wild Parsnip is its height and the color of its flowers. The mature plant typically grows to a height of three to five feet, sometimes reaching up to six feet. Its stems are stout, hollow, and notably grooved with vertical ridges running along their length.
The leaves are alternate on the stem and are pinnately compound, divided into multiple smaller leaflets. These leaflets are egg-shaped, often exhibiting deep lobes and sharply toothed edges. The plant produces flat-topped clusters of small, five-petaled flowers, known as umbels, which are a characteristic bright yellow color.
These yellow umbels are broad, spanning between two to six inches across, and appear from early June through late summer. The flowers develop on a tall stalk that emerges in the plant’s second year of growth. The whole plant has a yellowish-green color, and the stems are generally smooth and hairless.
Common Habitats and Growth Cycle
Wild Parsnip is a biennial plant, changing its appearance significantly throughout the season. During the first year, the plant exists as a low-lying cluster of leaves called a basal rosette. It stores energy in a long, thick taproot that resembles a cultivated parsnip and is one of the earliest plants to green up in the spring.
In its second year, the plant “bolts,” sending up the tall, grooved, flowering stalk that is the most visible and dangerous stage. After flowering and setting seed in mid-to-late summer, the plant dies. This species thrives in sunny, open environments and is frequently found in disturbed soil along roadsides, railway embankments, gravel pits, and abandoned fields. It cannot tolerate heavy shade, but it will readily invade trails and forest edges.
Confusing It With Other Plants
Wild Parsnip belongs to the carrot family (Apiaceae), which includes many other look-alikes that share the characteristic umbrella-like flower structure. The most common confusion is with Wild Carrot, also known as Queen Anne’s Lace, which has a similar appearance but a distinct difference in flower color. Queen Anne’s Lace produces white flowers and has a noticeably hairy stem, often featuring a single dark purple or reddish floret in the center of its white umbel.
Another frequent point of confusion is with Giant Hogweed, a much larger, highly toxic plant. Giant Hogweed is distinguished by its immense size, reaching heights of six to eighteen feet, and its massive white flower heads that can be two feet wide. Wild Parsnip is the wild form of the Edible Parsnip, and the toxic compound is present in both plants, though more concentrated in the wild variety. The distinction is often based on location, as the wild plant grows aggressively in untended areas while the cultivated plant is found in gardens.
Immediate Danger and Contact Safety
The danger stems from furanocoumarins, a group of chemicals present in the plant’s sap. When the sap contacts the skin and is exposed to ultraviolet (UV) light, the furanocoumarins are activated, causing phytophotodermatitis. This is a chemical burn, not an allergic reaction, meaning most people exposed to sap and sunlight will react painfully.
The reaction is not instant; symptoms usually appear hours later, peaking within 24 to 48 hours after exposure. Symptoms include severe redness, a burning sensation, and the formation of painful blisters that resemble second-degree burns. After the blisters heal, the affected skin often develops dark purple or brown patches, known as hyperpigmentation, which can last for months or even years.
If sap contact is suspected, the affected area must be immediately washed with soap and warm water to remove the phototoxic compounds. The effectiveness of washing decreases rapidly, dropping to only ten percent removal after thirty minutes. Afterward, the skin must be completely shielded from sunlight for at least 48 hours to prevent chemical activation and subsequent burning.