Carduus nutans (Nodding Thistle)

Plant Info
Also known as: Nodding Plumeless Thistle, Musk Thistle
Genus:Carduus
Family:Asteraceae (Aster)
Life cycle:biennial
Origin:Europe
Status:
  • Invasive - ERADICATE!
  • Noxious Weed
  • Prohibited or Restricted species
Habitat:sun; fields, along roads
Bloom season:June - October
Plant height:2 to 7 feet
Wetland Indicator Status:GP: FACU MW: FACU NCNE: FACU
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: indistinct Cluster type: round

[photo of flower] Flower heads are 2 to 3 inches across, purple to pinkish and often nod down, hence the common name. The showy bracts are rather large and generally triangular, in many layers spreading out away from the flower head, and are green or tinged purple. Flowers are single at the end of branching stems.

Leaves and stem: Leaf attachment: alternate Leaf type: lobed Leaf type: simple

[photo of leaves]  Leaves are up to 15 inches long at the base of the plant and deeply lobed, the lobes on lower leaves further divided into several smaller lobes, and becoming smaller and less deeply lobed as they ascend the stem. There are numerous spines along the wavy edges. Leaves are stalkless, mostly hairless except for the main veins on the underside, and may have a white cast on the edges, especially early growth rosettes.

[photo of stem] Leaf bases extend down the stem, forming spiny “wings”. Stems are many branched.

Notes:

Goldfinches are quite fond of Nodding Thistle (and all other thistles) for both the seed and the silks from the seed heads, which they use to line their nests. The large flower heads and broad, showy bracts make this species stand out from the rest, though closely related is Plumeless Thistle (Carduus acanthoides), whose flower heads are rather smaller, with narrow bracts. Nodding Thistle is on the noxious weed list for Minnesota, a common pasture/roadside pest. While not as obnoxious or as widespread as Plumeless Thistle, this species can invade high grade native habitats and is no doubt under-reported in the state. Of note is the MN Weed Advisory Group is recommending this species, currently a Prohibited-Control species, be removed from the noxious weed list because they have determined "infestations [are] primarily caused by human disturbance". The decision seems illogical, since that doesn't make it any less of a pest.

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More photos

Photos by K. Chayka taken at Long Lake Regional Park, Ramsey County. Photos courtesy Peter M. Dziuk taken at various locations around the Metro.

Comments

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

Posted by: Jane - Hennepin
on: 2011-05-28 14:00:57

Why are these and some of the other thistles on the restricted list? Is there an actual scientific justification for each species somewhere? I hope it's not something stupid like "they are prickly", especially if birds like them.

Posted by: K. Chayka
on: 2011-05-28 19:47:45

The non-native thistles are highly invasive and degrade native habitat. Regardless, many plants are on the noxious weed list because they are an agricultural pest plant that are problematic in grazing and crop fields. As for the birds, there are native thistles that they like just as well. What do you suppose they fed on before the weeds arrived?

Posted by: Rose - Cottonwood
on: 2015-05-20 16:53:30

Unfortunately, these nasty plants are found in Cottonwood County, though they were non-existent 15-20 years ago. The flowers are beautiful, no doubt, but the plants can really spread and take over. We have had most success in controlling them by removing all the blossoms and any buds showing any color and then chopping the plants off at the base. The plant has to be cut up in several smaller pieces because the stems hold a lot of water; any buds on the plant can still blossom and go to seed if the stems are left whole. The best treatment of the flower heads and buds is to dry them out and then burn them.

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