Conium maculatum (Poison Hemlock)

Plant Info
Also known as:
Genus:Conium
Family:Apiaceae (Carrot)
Life cycle:biennial
Origin:Europe
Status:
  • Invasive - ERADICATE!
Habitat:sun; moist soil, along shores, fields, roadsides, disturbed soil
Bloom season:June - August
Plant height:3 to 8 feet
Wetland Indicator Status:GP: FACW MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 5-petals Cluster type: flat

[photo of flowers] Flowers are in flat clusters (umbels) about 3 inches across. Individual flowers are about 1/8 inch across and have 5 white petals of unequal size, usually notched and folded lengthwise. There are 5 stamens with white to yellowish tips, 1 between each petal. One plant has many clusters, at the ends of branching stems. The stems persist through the winter.

Leaves and stem: Leaf attachment: alternate Leaf type: compound

[photo of leaves] Leaves are 2 or 3 times compound, up to 12 inches long and wide, generally triangular in outline, becoming smaller as they ascend the stem. Leaflets are divided and fern-like, to 2 inches long and 1 inch wide.

[photo of stem] The main stem is light green and covered in purple spots

Fruit: Fruit type: seed without plume

[photo of fruit] Fruit is an egg-shaped pod, about 1/8 inch long, covered in wavy ribs. It splits into 2 seeds.

Notes:

All parts of Poison Hemlock are deadly poisonous. This plant is easy to distinguish from other members of the carrot family by the feathery, double compound leaves, and the purple spotted stem.

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More photos

Photos taken at Long Lake Regional Park, New Brighton, MN July 2007 and June-July 2008

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Mark - Vista Hills Park, Maplewood, MN
on: 2011-06-04 13:48:01

Found on both sides of the path leading to Marnie St from the southwest corner of the park, a couple hundred feet from the street.

Posted by: K. Chayka
on: 2011-06-18 12:42:54

Based on the images you sent, I would say what you found was Not poison hemlock after all, but sweet cicely. Many members of the carrot family have similar leaves, i.e. deeply divided and a bit feathery. Queen Ann's lace and Japanese hedge parsley are others. Looking at various plant parts and paying attention to small details can help narrow down an ID.

Posted by: Xenia - washington co
on: 2012-03-24 11:02:32

Chayka is right about them being sweet cicely and not poison hemlock one easy way to identify this plant is its mouse urine like smell

Posted by: Zed - Olmsted County near Oronoco
on: 2015-07-01 12:57:29

I believe Ive located this plant on the north side of Lake Shady along 5th ST. N.W. The approximate size of the patch is 10 x 10 I have pics if you'd like to confirm my findings. Zed

Posted by: K. Chayka
on: 2015-07-05 10:00:38

Zed, there are a number of carrot species with similar flowers and growth habits. We prefer you post pictures on our Facebook page if possible, that way others can learn from it, too.

Posted by: John Z - St Paul
on: 2017-07-02 16:01:34

Katy, thank you for your comments above. I was trying to figure out a new plant that was showing up in our yard (St. Paul) this year. Looking at my wildflower guide, it seemed to be poison hemlock. But then I checked your website and figured out that it's Japanese Hedge Parsley. I will pull it out.

Posted by: John K - Rosemount
on: 2017-07-07 16:16:42

I found and took pictures of several suspect plants on the walking paths around Rosemount High School. I believe this to be Poison Hemlock.

Posted by: K. Chayka
on: 2017-07-07 16:38:40

John K, while poison hemlock is rapidly spreading in MN, it is not the only non-native white carrot found in disturbed areas such as along paths. Poison hemlock has more recently been seen traveling along waterways, though it is also found along transportation corridors such as railroad rights-of-way. More common in the Metro area is Torillis japonica, Japanese hedge-parsley, which is becoming common in wooded parks.

Poison hemlock is quite robust, growing over 6 feet tall with a smooth, stout, purple spotted stem, hairless leaves and hairless, ribbed seeds. Japanese hedge-parsley is 3-4 feet tall with a hairy stem, hairy leaves, and fruit with hooked hairs.

Posted by: Susan S - St. Louis County
on: 2017-08-03 19:00:31

Along the St. Louis River trail near Perch Lake in far west Duluth. Also on state or county forest land southwest of Hwy 23 near Hwy 18 in the Wrenshall area. In addition, some very large plants in there look like Giant Hogweed. There are also a few small p. hemlock plants growing on a trail off Hwy 210 N/NW of Hwy 23.

Posted by: K. Chayka
on: 2017-08-04 17:51:16

Susan, there are no confirmed occurrences of giant hogweed in Minnesota. The common cow parsnip (Heracleum lanatum)is often mistaken for giant hogweed and that is more likely what you found. Poison hemlock is being tracked in MN. You can open an account and post your finding at EDDMapS but you must include photos that can confirm it is what you think it is. Images showing the finely divided leaves and purple-spotted stem are best. There have been quite a number of mid-IDs for these plants. Confirmation is necessary.

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