Cow Parsley (Anthriscus sylvestris) is a familiar sight, often lining roadsides and hedgerows with its frothy white flowers in spring. This common plant belongs to the Apiaceae family, also known as the carrot or parsley family. While Cow Parsley is generally considered non-toxic, the Apiaceae family includes some of the most dangerous plants. The striking similarity in appearance between this benign plant and its deadly relatives makes accurate identification a matter of public safety. Knowing the subtle differences between these plants is essential for safety.
The Toxicity Status of Cow Parsley
Cow Parsley (Anthriscus sylvestris) is not considered poisonous to humans or livestock when ingested. Although used in traditional cooking, its flavor is often described as unremarkable. The plant’s leaves and stems are generally non-toxic and do not contain the deadly alkaloids or phototoxic compounds found in its look-alikes.
Some individuals may experience a mild, short-lived skin rash known as contact dermatitis after handling the plant’s sap, particularly if they have sensitive skin. This reaction is minor and should not be confused with the severe, painful burns caused by truly phototoxic plants. Unlike its hazardous relatives, Cow Parsley does not make the skin hypersensitive to sunlight. The primary risk associated with Cow Parsley is the extreme danger of misidentifying it for a toxic species.
Dangerous Plants Mistaken for Cow Parsley
The primary danger arises from Cow Parsley’s resemblance to highly toxic species, which also feature the characteristic umbrella-like flower clusters. Two of the most hazardous look-alikes are Poison Hemlock (Conium maculatum) and Giant Hogweed (Heracleum mantegazzianum). These plants pose distinct threats: ingestion toxicity and severe contact phototoxicity, respectively.
Poison Hemlock is one of the deadliest plants in the world, containing toxic piperidine alkaloids such as coniine, which affect the nervous system. Ingestion of any part of the plant can lead to symptoms like muscle tremors, vomiting, and eventually, respiratory failure due to paralysis of the breathing muscles. The toxic compounds are present throughout the plant, with the highest concentrations often found in the seeds.
Giant Hogweed presents a risk through external contact rather than ingestion. Its sap contains furanocoumarins, chemicals that cause a severe skin reaction known as phytophotodermatitis when exposed to sunlight. Contact followed by sun exposure results in painful, blistering burns that can cause long-lasting scars and increased sensitivity to light. Hemlock Water Dropwort (Oenanthe crocata) is a third dangerous look-alike; it is highly toxic, particularly its parsnip-like roots, and can be lethal if consumed.
Telling the Plants Apart
Accurately distinguishing Cow Parsley from its toxic relatives requires close attention to specific physical characteristics, as the overall shape is deceptively similar. The stem is the primary distinguishing feature between Cow Parsley and Poison Hemlock. Cow Parsley stems are pale green, covered in fine, soft hairs, and often have a distinctive groove, giving them a celery-like appearance.
In contrast, the stem of Poison Hemlock is smooth, hairless, and covered in distinctive purple or reddish-purple blotches or spots. The odor of the crushed foliage is another key identifier; Cow Parsley has a mild, pleasant, anise-like, or parsley scent. Conversely, Poison Hemlock emits a strong, unpleasant, musty, or mouse-urine-like odor when its leaves or stem are bruised.
Giant Hogweed is differentiated primarily by its massive scale and stem texture. While Cow Parsley typically grows no taller than five feet, Giant Hogweed can tower up to 15 feet in height with leaves spanning five feet across. The stem of Giant Hogweed is thick, ridged, and covered in coarse, stiff white hairs, along with prominent purple or reddish blotches that are more raised than the smooth spots on Poison Hemlock.
What to Do in Case of Exposure
Immediate action is necessary if exposure to a poisonous look-alike is suspected, either through ingestion or skin contact. If ingestion of a toxic plant like Poison Hemlock is suspected, immediately contact your local emergency medical services or a poison control center for professional guidance. Do not wait for symptoms to appear before seeking help.
If skin contact with the sap of a phototoxic plant like Giant Hogweed is suspected, the affected area must be washed immediately and thoroughly with soap and cold water. Crucially, the exposed skin must be covered completely and protected from sunlight for at least 48 hours to prevent the severe blistering reaction. If sap enters the eyes, they should be rinsed continuously with water for at least 10 minutes, and medical attention should be sought right away. When contacting medical professionals, try to describe the plant or bring a sample for positive identification, provided you can do so without further exposure.