Wild Parsnip
Wild parsnip (Pastinaca sativa) is an invasive biennial plant native to Europe and Asia. It was introduced to North America for its edible root but has since spread aggressively, especially in disturbed areas. This plant poses significant risks to both the environment and human health due to its ability to outcompete native species and its phototoxic sap.
Appearance:
Wild parsnip grows up to 4-6 feet tall and has a thick, grooved stem that is green or slightly purple. The leaves are pinnately compound, with 5-15 sharply toothed leaflets. In its second year, wild parsnip produces a tall, flowering stalk topped with a flat-topped cluster (umbel) of small, yellow flowers, which bloom from June to July. The plant's root is a long, tapered taproot, similar in appearance to a cultivated parsnip.
Habitat and Spread:
Wild parsnip thrives in a variety of habitats, including roadsides, fields, pastures, and riverbanks. It prefers full sunlight and well-drained soils but can tolerate a range of conditions. The plant spreads primarily through its seeds, which are dispersed by wind, water, and human activity. Each plant can produce thousands of seeds, which can remain viable in the soil for several years, contributing to its rapid spread and persistence.
Impacts:
- Ecologically, it outcompetes native plants, reducing biodiversity and altering habitats. Its dense growth can dominate an area, crowding out other species.
- For humans, the sap of wild parsnip contains chemicals called furanocoumarins, which cause phytophotodermatitis—a severe skin reaction when exposed to sunlight. This can result in painful blisters, rashes, and long-lasting skin discoloration.
Control and Management:
- Mechanical Control: such as mowing or cutting, can be effective if done before the plant flowers to prevent seed production. However, care must be taken to avoid skin contact with the sap.
- Chemical Control: Herbicides can also be used, particularly for large infestations, but should be applied before the plant sets seed
Potential Dangers:
Phytophotodermatitis:
- Human Health Risk: The most significant danger of wild parsnip is its ability to cause phytophotodermatitis. When the plant's sap comes into contact with the skin and is then exposed to sunlight, it triggers a chemical reaction that can lead to severe skin irritation. Symptoms include:
- Painful Blisters: Large, fluid-filled blisters can form on the affected skin, resembling severe burns.
- Rashes: Redness and inflammation often accompany the blisters.
- Long-lasting Skin Discoloration: Even after the blisters heal, the affected areas can remain discolored (brown or purplish) for months or even years.