How to Identify ‘The Most Deadly Plant in North America’

The arrival of summer in the Hudson Valley means the ability to spend more time outdoors. Unfortunately, there are some invasive (as well as native) plants that could put a serious end to the fun.

Recently, the United States Fish and Wildlife Service took to social media to warn outdoor enthusiasts about three specific plants: hogweed, parsnip, and hemlock. While they all look strikingly similar (and are all potentially harmful), one stands out among the rest.

Wild Parsnip and Cow Parsnip in the Hudson Valley

Both wild parsnip and cow parsnip (above) are the least dangerous plants of the group. Contact with either plant can cause skin irritation including blisters and rashes. See where they grow in the Hudson Valley below.

Differences Between Wild Parsnip and Cow Parsnip

Cow parsnip is usually taller (plants can grow up to ten feet) while wild parsnip is generally no taller than five feet. Cow parsnip is also native to the area while wild parsnip is invasive.The effects of both, however, pale in comparison to hogweed (below).

Giant Hogweed in New York State

Giant Hogweed lives up to its name, growing up to eighteen feet in some cases. As with parsnip, contact with the plant can lead to blisters and rashes, but effects can be more severe and may lead to scarring of the skin or even blindness.

Where Does Giant Hogweed Grow in New York?

Giant Hogweed is an invasive plant that can be found in several counties across New York State, but so far that excludes the Hudson Valley (above). Unfortunately that is not the case for two deadly plants that look strikingly similar.

Poison Hemlock in the Hudson Valley

Poison hemlock is as serious as its name suggests. The USFWS describes the plant as "three to eight feet tall [with] stems that are hairless and hollow with ridges and purple spots" (above).

Where to Find Poison Hemlock in the Hudson Valley

Poison hemlock has been found in Ulster and Orange counties, and residents are warned that ingesting even small parts of the plant can cause death in both humans and animals. The only species deadlier is the spotted water hemlock (below).

Spotted Water Hemlock in the Hudson Valley

According to the USFWS, spotted water hemlock is known as "the most deadly plant in North America". Identifying characteristics include "stems that are smooth and hollow [that] may vary in color and pattern, from solid green or purple to green with purple spots or stripes".

Where to Find Spotted Water Hemlock in the Hudson Valley

Spotted water hemlock is native to the United States and can be found across New York, including in the Hudson Valley. Residents are also urged to keep curious pets away from the plant as it can be harmful to all living things

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Check out more photos of poison hemlock below, then keep scrolling to see the opposite end of the spectrum: plants that can actually help your garden.