Chaiturus marrubiastrum (False Motherwort)

Plant Info
Also known as: Horehound Motherwort
Family:Lamiaceae (Mint)
Life cycle:biennial
  • Weedy
Habitat:part shade, sun; disturbed soil; lawns, woods, stream banks, fields, roadsides, waste places
Bloom season:July - October
Plant height:1 to 3 feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: irregular Flower shape: tubular Cluster type: whorled

[photo of flower clusters] Dense clusters of stalkless flowers surround the stem at the leaf nodes in the upper half or more of the plant and along branching stems. Usually only a few flowers in a cluster are open at the same time.

[close-up of flowers] Flowers are pale pink to lavender to whitish, tubular, about ¼ inch long. The upper lip extends out like a hood, its outer surface covered in short, white hairs. The lower lip is 3-lobed with the center lobe largest; there are usually a few reddish-purple spots near the mouth of the tube. Purple stamens and a white style arch along the inside of the upper lip.The calyx is green, minutely hairy, about as long as the floral tube, and has 5 sharply pointed lobes with spiny tips.

Leaves and stems: Leaf attachment: opposite Leaf type: simple

[photo of mid-stem leaves] Leaves are opposite, finely hairy, and vary in size and shape as they ascend the stem. The lower leaves are up to 3½ inches long, nearly round to egg-shaped, bluntly pointed at the tip, coarsely toothed, on stalks up to about ¾ inch long. Leaves become more lance-elliptic as they ascend the stem, the uppermost leaves often with just a few teeth near the tip. Stems are square, variously hairy, usually branched. Plants create colonies from spreading rhizomes.

Fruit: Fruit type: seed without plume

[photo of developing fruit] The calyx persists through winter and turns brown and quite stiff when dry, the lobes becoming rather sharp to the touch. Inside are 4 1-seeded nutlets.


False Motherwort, formerly Leonurus marrubiastrum, is a Eurasian introduction that is not known to be widespread in Minnesota, but we suspect it is probably under-reported like many other weeds. The first report was in Anoka County in 1998, the second 10 years later in Goodhue County, then not again until 2021 when the subject came up in a Facebook group, where it was reported to be widespread in southeastern South Dakota. That triggered additional Minnesota sightings, in Hubbard and Hennepin counties. Our images came from the Hennepin County site, at Green Circle Park in Minnetonka.

False Motherwort resembles the much more common Motherwort (Leonurus cardiaca), which has lobed, maple-like leaves and its flowers have long hairs on the outer surface and a narrow, folded lower lobe. Also similar is the native Wild Mint (Mentha arvensis, a.k.a. M. canadensis), which has leaves more uniform in size and shape that are wonderfully aromatic when crushed.

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More photos

Photos by K. Chayka taken in Hennepin County.


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

Posted by: Timothy Johnson - Anoka County
on: 2021-08-26 20:08:00

Blooming on August 8, 2021 on Large Island below Coon Rapids Dam on the Mississippi River

Posted by: Gabriel Miller - Welch township, MN
on: 2022-01-06 13:22:05

We discovered this plant in 2020 within shaded floodplain woods in a narrow band about 10-20 feet from the river shoreline, though it seems to be mostly absent the further you get from the shoreline. May be related to a flood line or microclimate variables? Roughly 50% coverage on average where it exists.

Posted by: Keanna Kerrigan - Goodhue County
on: 2023-04-13 15:49:50

I found False Motherwort in a wooded upland area on top of a bluff overlooking the St. Croix River. It was growing side by side with Common Motherwort. They look very similar, and I'm wondering if part of the reason False Motherwort is under-reported because it can get confused with Common Motherwort.

Posted by: j g - anoka county
on: 2023-10-03 09:30:31

I came here to look up horehound and found this. I never knew there was a false motherwort. We have what I think is motherwort growing on our property. The first time I saw it, I let it grow because 'it's pretty'. The next year I regretted that decision. But now I'll have to look and see if what we have is false or not false. I haven't seen it bloom in years because I pull it before it flowers. Something on my list for next year.....

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