KISMA

Invasive species have the potential to cause harm to the environment, the economy, and human health. Wild parsnip (Pastinaca sativa) is one of the invasive plants managed by the Keweenaw Invasive Species Management Area (KISMA) that can affect human and animal health. Though it is considered an invasive species now, it was initially brought to the U.S. from Eurasia in the 1600s as a food source. It eventually made it to Michigan in the 1800s. Shortly after its introduction, wild parsnip escaped into fields and pastures, securing its place as an invasive species. While wild parsnip may not be as effective at outcompeting native plants as other invasives managed by KISMA, it can be quite harmful to humans and animals in the areas it invades, and, given time, it can dominate the infested ecosystem.

Skin reaction

to wild parsnip

When touched, wild parsnip can cause phytophotodermatitis. Phytophotodermatitis is a reaction between a chemical within the plant’s sap and UV rays from the sun that causes burning, blistering, and rashes on your skin-this is a chemical burn similar to burns caused by heat. The impact of this interaction typically happens within 48 hours of exposure, with skin discoloration lasting up to 2 years, according to the Michigan Natural Features Inventory (2018) Best Control Practice Guide document for wild parsnip (https://mnfi.anr.msu.edu/invasive-species/WildParsnipBCP.pdf). In addition, Campbell and others reported in the British Medical Journal (1982; http://www.jstor.org/stable/29505585) that wild parsnip can be especially harmful to children who play in fields where the plant is present.

Animals are also susceptible to the dermal effects of wild parsnip. Wild parsnip has been recorded on livestock to cause blistering, burning, and rashes similar to those found on humans. In addition, livestock have experienced weight loss and decreases in fertility when they consume large quantities of wild parsnip, according to the 2019 study completed by Stegelmeier et al. (https://www.sciencedirect.com/science/article/pii/S0041010119301801). Therefore, due to the adverse effects of wild parsnip, if animals are grazing in areas where this plant is present, it is crucial to ensure that other food sources are available to them and that they are not solely eating wild parsnip.

Wild parsnip

identification

Wild parsnip is in the same family (Apiaceae) as carrot and Queen Anne’s Lace (Daucus carota). It has an extensive list of look-alikes, including Queen Anne’s Lace, cow parsnip (Heracleum maculatum), golden Alexander (Zizia aurea), and prairie golden Alexander (Zizia aptera). Queen Anne’s Lace has white flowers, as opposed to the yellow flowers of wild parsnip, and the leaves of Queen Anne’s Lace are more “feathered” than wild parsnip leaves. Cow parsnip, a native, is similar in size to wild parsnip but has white flowers instead of yellow. While golden Alexanders and prairie golden Alexanders have yellow flowers like wild parsnip, both are natives and can be distinguished from wild parsnip by their leaves.

Wild parsnip grows in open and disturbed areas, fields, and pastures. According to the Midwest Invasive Species Network, the defining characteristics of wild parsnip include:

• It is a biennial. It is a small basal rosette in the first year and can grow 5 feet tall in the second year.

• The leaves are 6 inches long, alternate, and pinnately compound with 5-15 toothed leaflets that resemble a mitten.

• The individual flowers are small, yellow, and have 5 petals. The arrangement of the flowers looks like an umbrella, called an umbel, roughly 6 inches wide for larger flowers.

• The stems are green, unbranched, grooved, have some hairs, and are thick.

• The taproots are long and resemble a white carrot. This is the edible part.

• The seeds are oval, with one flat side and one side with ridges.

Safe removal

The best way to protect your children, pets, livestock, and yourself from wild parsnip is to remove the plant. Safe removal includes wearing long sleeves, pants, and gloves, but really you just don’t want to get the sap on your skin and expose that to sunlight. Some people have reported doing removals at night and then showering. KISMA recommends manual treatment methods for small infestations of wild parsnip. When removing the plant, digging or pulling up as much of the root as possible is vital. If the taproot does not come out when pulled, it should be cut with a sharp shovel a few inches below the soil’s surface. Make sure to dispose of all plant material properly by bagging or pilling. For larger infestations, mechanical treatment, such as mowing, is the best option. Mowing twice a year is effective when completed over consecutive years. Mowing should occur once after the plant has flowered but before it has produced seeds and then once again in the fall. Wild parsnip seeds can last up to four years, so treatments must be repeated until the seed bank is depleted.

Additional resources

• For more information on wild parsnip identification and management, visit KISMA’s website: https://www.mtu.edu/kisma/terrestrial-invasive-species/wild-parsnip/

• For information on chemical controls, visit the Michigan Natural Resource Inventory: https://mnfi.anr.msu.edu/publications/best-control-practice-guides

• For more information on wild parsnip identification and similar species, visit: http://www.misin.msu.edu/facts/detail/?id=40

Research by Evan Andrews (ewandrew@mtu.edu), working on undergraduate degree in Forestry, Erin Mauk (ermauk@mtu.edu), completed Wildlife Ecology and Conservation undergrad degree; Sigrid Resh (scresh@mtu.edu) Coordinator, Keweenaw Invasive Species Management Area (KISMA), and Research Assistant Professor; Michigan Technological University