Heracleum maximum (Common Cow Parsnip)

Plant Info
Also known as: American Cow-parsnip
Genus:Heracleum
Family:Apiaceae (Carrot)
Life cycle:perennial
Origin:native
Habitat:part shade, sun; moist fields, thickets, streambanks
Bloom season:May - July
Plant height:4 to 10 feet
Wetland Indicator Status:GP: FAC MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county 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) 4 to 8 inches across, each cluster made up of 15 to 30 smaller clusters (umbellets) of up to 30 flowers. Individual flowers are about ¼ inch across with 5 white petals notched at the tip. The flowers on the outer edge are larger and have more deeply divided petals of unequal size. There are 5 white tipped stamens surrounding the creamy button center.

[photo of umbellet bracts] At the base of the umbel and each umbellet are 4 or more green, lance-linear bracts as long as or longer than the individual flower stalks, but they tend to drop off by fruiting time. One plant has a few to many flower clusters, at the tips of branching stems and arising from the upper leaf axils.

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

[photo of leaves] Leaves are palmately compound in 3's, softly hairy, with fine sharp teeth around the edges, to 18 inches long and wide near the base of the plant, becoming smaller as they ascend the stem. The end leaflet is largest and lobed in 3 parts; each lobe may be further divided. Attachment is alternate.

[photo of sheath and stem] The leaf stalk is long and sheathed where it clasps the stem. Stems are single, erect, few to many branched, stout and hollow. Stems, leaf stalks and sheaths are all covered in short fine hairs, though may be sparsely hairy in the upper plant.

Fruit: Fruit type: seed without plume

[photo of fruit] Fruit is flattened, oval to heart-shaped, ¼ to ½ inch long, matures to brown and splits into 2 seeds.

[close-up of seed] Seeds are ribbed along the edges, have 3 or 4 vertical lines and are often finely hairy.

Notes:

Cow Parsnip, formerly Heracleum lanatum, is present throughout Minnesota, often seen in late spring and early summer along roadsides in wet ditches. It has broader flower clusters than most other members of the carrot family; that and the large leaves make it easy to ID. Cow Parsnip is the native counterpart to the highly invasive non-native Giant Hogweed (Heracleum mantegazzianum), which is not yet known to be present in Minnesota but is making its way here. Giant Hogweed really is a giant, growing up to 20 feet tall with stems 2 to 4 inches in diameter and compound leaves 3 to 10 feet(!) wide. Like Wild Parsnip (Pastinaca sativa), Giant Hogweed sap causes phytophotodermatitis, resulting in serious burns and painful blisters when affected skin is exposed to sunlight. Cow Parsnip can have the same effect.

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More photos

Photos by K. Chayka taken at Wild River State Park, Chisago County, and in Dakota, Winona and Yellow Medicine counties. Photos by Peter M. Dziuk taken at locations across Minnesota.

Comments

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

Posted by: Barb - southwest MN
on: 2010-08-04 20:22:13

We have seen these growing in many nearby parks and recreational areas. I always warn my children and grandchildren to stay away from them because they so closely resemble their very poisonous relatives. Besides, contact can make skin sensitive to the sun and cause irritation.

Posted by: Anne - North Shore, specifically Sugar Loaf Cove
on: 2014-04-24 19:12:09

or could it be giant hog weed?

Posted by: K. Chayka
on: 2014-05-31 17:49:04

As far as we know, giant hogweed is not confirmed in MN. Cow parsnip is common, though

Posted by: Mae - near Lake of the Woods
on: 2014-06-23 16:02:05

I've seen several of these plants, at least I think they are cow parsnips. I thought at first they might be giant hogweed

Posted by: sharon - Lake Vermilion, Tower, Mn.
on: 2014-08-18 19:55:06

This is a beautiful plant. I look forward to it maturing and blooming and then, over night, it is chewed down most likely by the neighborhood deer. I don't touch it as I am concerned about a dermatitis under correct conditions.

Posted by: Beth - Superior Hiking Trail between Hwy 1 and Tettegouche
on: 2015-07-13 08:17:27

They were at least 5 1/2 feet tall. Beautiful. So glad I don't touch wild flowers. I didn't know about the skin irritation this one creates.

Posted by: Carole - Howard Lake
on: 2015-07-20 12:57:28

Cow Parsnips are not as tall as Giant Hogweed. Also, it flowers later. https://www.youtube.com/watch?v=sysmrqw4sEo

Posted by: luciearl - Fairview Township
on: 2017-04-30 20:57:43

I have seen these growing in the ditch. After hearing a baby cub crying in the woods, I wondered what black bears eat in the spring. This was listed as one of the foods. I would like to plant more as the Pillsbury Forest continues to shrink.

Posted by: Leah B - West Medicine Lake Park, Plymouth
on: 2017-06-27 20:43:54

I noticed quite a few of these plants growing along the trails across the road from West Medicine Lake Park. I was afraid at first that they were Giant Hogweed. After a photo comparison, I can see that it is Cow Parsnip growing near the trail.

Posted by: Joyce Meyers - Rollingstone
on: 2018-06-24 20:41:50

Have cow parsnip growing on a bank behind our house. They get pretty big, and I haven't seen any birds or butterflies land on them, blooming now in late June.

Posted by: Scott Lund - Elk River area towards Twin Lakes
on: 2018-06-25 06:29:25

As of 6/24/18 West of Elk River on Twin Lakes Road there appears to be blossoming plants pretty much everywhere off the road a hundred feet or so. The walking trail right off the swim beach at Twin Lakes has many 6 foot plus plants in full bloom all within reach for full inspection.

Posted by: Wanda davies - Lutsen
on: 2018-07-29 20:26:36

I’ve not seen this plant around here prior to this year. Now it seems to be all over close to the lake.

Posted by: Nancy Smith - Duluth
on: 2018-08-05 12:25:18

I'm pretty sure I've identified one (1!) cow parsnip plant growing on Wahl Road, in Lakewood Township. I wasn't paying attention when it flowered to remember whether it had yellow flowers, but the seeds seem distinctive now that I've found an actual closeup photo of the seeds.

Posted by: Gary - Carlton County
on: 2018-10-18 21:23:57

I notice once again that Carlton County is a white square on the map. This species is common here along the edges of wetlands and in ditches near roadsides and old railroad grades. I've seen Virginia Ctenucha moth nectaring at the flowers.

Posted by: Julie Keitel - Whitewater State Park St Charles MN
on: 2019-06-10 21:32:54

June 19, quite prevalent along the river banks.

Posted by: Kimberly E. - Pilot Grove Lake - Faribault County
on: 2019-06-17 11:57:31

Growing in the northwest corner of Pilot Grove Lake, in the ditch near the tree grove.

Posted by: dean - Winona and Wabasha counties
on: 2019-07-01 22:09:51

I see it along hwy 61 in Winona and Wabasha counties. It's basically EVERYwhere across the river in WI, so it's not surprising to find it here I guess.

Posted by: Jeff - Grand Marais
on: 2019-07-05 14:56:59

We've always erroneously called this "Birdock." Imagine my surprise to find out it's a parsnip species! It's very common along the North Shore up around to Wawa.

Posted by: Cree Bradley - Lake County - Mitiwan Lake Road, Near Rat Lake
on: 2019-07-20 08:42:58

A cluster of it is along the east side of Mitiwan Lake Road, with a couple single stems along the west side if Mitiwan Lake Road. A Lake County road crew asked me about the invasive plant along Mitiwan, and what could be done about it. I was grateful for this resource to accurately identify it and learn it's not an invasive. I will pass the information along to the crew.

Posted by: patrick fleming - Lake Elmo, Washington County
on: 2020-05-29 18:24:15

I have several of these plants in my backyard prairie. The prairie is restored, but I did not plant this one.

Posted by: Ronald Johannsen - Trenton Lake So. Mn.
on: 2020-06-04 19:47:50

Now blooming many in area, showy.

Posted by: Jesse - Buffalo river state park
on: 2020-06-14 17:19:55

Flowing at buffalo river state park on June 14. HUGE

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