Articles

Is it Poison Hemlock or Wild Chervil?

Poison hemlock and wild chervil look very similar and resume growth early in the spring. Learn more about these look-alike weeds.

Updated:

April 16, 2024

A mixture of poison hemlock and wild chervil along a wooded area. (Source: D. Lingenfelter, Penn State Weed Science)

Basic Information

Poison hemlock (Conium maculatum) and wild chervil (Anthriscus sylvestris) are in the carrot or Umbelliferae family and the leaves and foliage resemble carrot and parsley.
Both are very invasive and spread rapidly if left unchecked.

Wild carrot (also called Queen Anne’s lace), wild parsnip, spotted water hemlock, and purple-stemmed angelica can sometimes be confused with these species because they are in the same family and have some similar features.
Cow parsnip and giant hogweed are also part of the same family; however, they are much larger in stature and should not be easily mistaken for them.

Poison hemlock germinates from seed and is a biennial plant.
Wild chervil grows as a biennial or a short-lived perennial.
Both species begin with a basal rosette of leaves during its first year.
Once they overwinter, in late April/early May, they bolt into an erect branched plant producing prominent white flowers in an umbel, generally in June and July. They set and drop seeds soon after.
Poison hemlock only reproduces by seed and its taproot dies as the main plant desiccates.
Wild chervil mostly originates from seed; however, it can sometimes produce a crown and thus regrows from that structure.

Both have fern-like, glossy green, lacy leaves in the rosette stage and can be difficult to distinguish from each other.
Poison hemlock has a hairless, hollow main steam with purple blotches/spots which branches. Stems may turn purple as it matures. Its large flower structures are composed of many smaller white flowers. Plants typically grow 2 to 6 feet tall and have a parsnip-like odor when the leaves are crushed.
Wild chervil also has a hollow stem, but its stems are deeply grooved and have velvety hairs, especially on the lower stem. Chervil ranges from 18 inches to 4 feet tall. It also has a large umbel with many small white flowers which eventually produce stubby, finger-like seed clusters.

In general, poison hemlock is more toxic than wild chervil. The sap of poison hemlock has the potential to cause dermatitis (skin irritation) in some people. So be sure to wear protective clothing and gloves when handling the plant or when weed-whacking.
Poison hemlock contains toxic alkaloids. It is poisonous when ingested by humans and livestock. The plant contains several closely related pyridine alkaloids, the main one being coniine, a colorless, volatile, and strongly alkaline oil. All parts of the plant are poisonous, and some studies have shown toxicosis at 0.25% fresh weight. (of the animal’s weight) for horses and 0.5% for cattle. That would be 2.5 to 5 lb. of material per 1000 lb. animal. Mature seeds are the most poisonous. Significant poisoning can result in muscle paralysis and suffocation.

Both typically grow along roadsides, fencerows, fallow areas, and waterways. Poison hemlock can also infest pastures and no-till fields.

Individual plants can be easily dug out with a shovel.
Larger infestations can be cut with a mower or string trimmer or may require the use of a herbicide.
Several herbicides are effective for control. Herbicide applications are most effective when they are sprayed in the fall when poison hemlock is in the rosette stage or before it bolts in the spring. Effective herbicides include 2,4-D + dicamba, Crossbow (2,4-D+triclopyr), or glyphosate as a spot treatment.

Poison hemlock is native to Europe, northern Africa, and western Asia and was introduced to North America as an ornamental garden plant. In the annals of history, it was noted that the Greek philosopher Socrates chose to drink poison hemlock tea for his execution.
Wild chervil is also an introduced plant to the U.S. as an ornamental and for use in cooking.