Chaiturus marrubiastrum (False Motherwort)

Plant Info
Also known as: Horehound Motherwort
Genus:Chaiturus
Family:Lamiaceae (Mint)
Life cycle:biennial
Origin:Eurasia
Status:
  • 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

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

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.

Notes:

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.

Please visit our sponsors

  • Wild Ones Twin Cities Chapter

Where to buy native seed and plants ↓

Map of native plant purveyors in the upper midwest

  • Natural Shore Technologies - Using science to improve land and water
  • Itasca Ladyslipper Farm - Native orchids, container grown
  • Prairie Restorations - Bringing people together with the land
  • Landscape Alternatives - Distinctive Native Plants since 1986!
  • Shop for native seeds and plants at PrairieMoon.com!

More photos

Photos by K. Chayka taken in Hennepin County.

Comments

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

Post a comment

Note: All comments are moderated before posting to keep the riff-raff out. An email address is required, but will not be posted—it will only be used for information exchange between the 2 of us (if needed) and will never be given to a 3rd party without your express permission.

For info on subjects other than plant identification (gardening, invasive species control, edible plants, etc.), please check the links and invasive species pages for additional resources.



(required)




Note: Comments or information about plants outside of Minnesota and neighboring states may not be posted because Id like to keep the focus of this web site centered on Minnesota. Thanks for your understanding.