field thistle

(Cirsium discolor)

Conservation Status
field thistle
  IUCN Red List

not listed


N5? - Secure

SNR - Unranked


not listed

Wetland Indicator Status
  Great Plains

FACU - Facultative upland


FACU - Facultative upland

  Northcentral & Northeast

UPL - Obligate upland


Field thistle is a 36 to 84 tall, erect, biennial or short-lived perennial forb that rises on a single stem from a slightly thickened taproot and fibrous roots.

The stems are erect with few to many ascending branches. They are covered with long, white, spreading, unmatted, soft hairs when young, becoming almost hairless as they age. They are not winged and do not have spines.

In the first year the plant appears as a rosette of basal leaves. In the second year it sends up a flowering stem.

Basal leaves are firm, broadly lance-shaped to egg-shaped or elliptic in outline, 4 to 20 long, and 1½ to 9 wide, but usually no more than 10 long and 5 wide. They are bluntly angled or sometimes rounded at the tip and taper at the base to a winged leaf stalk. They are deeply lobed (pinnatifid), the lobes cut more than halfway to the midrib. The upper surface is green and hairless or moderately covered with stiff, straight hairs. The lower surface is white and densely covered with felty hairs. The margins are coarsely toothed, spiny, and rolled under. Basal leaves are usually absent at flowering time.

Stem leaves are similar, alternate, stalkless, 1½ to 10 long, and to 5 wide, becoming smaller as they ascend the stem. The leaf bases are sometimes somewhat clasping but do not extend down along the stem. The leaves at the branch tips are smaller. The upper leaves are well developed.

The inflorescence is usually a single flower head, sometimes a few flower heads, at each branch tip. The flower heads are stalkless or on short stalks (peduncles). The peduncles are leafy, up to 2 long, and are not overtopped by upper stem leaves. Each head is subtended by a ring of spiny, leaf-like bracts. These bracts arch upward and encage the developing flower head at first, spreading gradually as the head matures.

The whorl of bracts at the base of the flower head (involucre) is egg-shaped to broadly cylinder- or bell-shaped, ¾ to 1 long, and to 13 16 wide, as long or longer than wide. It usually has a few cobwebby hairs. The bracts of the involucre have a 1 16 to 3 16 long, straw-colored spine at the tip.

The flower heads are 1½ to 2 wide. There are numerous pale, pinkish-purple, tubular flowers.

The fruit is a tan to brownish, to 3 16 long achene (cypsela). The cypsela has a straw-colored collar near the tip and a tuft of white hairs at the tip.




36 to 84


Flower Color


Pale pinkish-purple


Similar Species


Bull thistle (Cirsium vulgare) stems have wings with spiny margins. The leaf bases extend down along the stem. The underside of the leaf is green.

Flodman’s thistle (Cirsium flodmanii) is a shorter plant, usually no more than 32 in height. The stems remain densely white tomentose with age. The upper leaf surface is tomentose when young. The flower head is not subtended by a ring of spiny bracts. The flower head is smaller, no more than 1 wide. The collar on the cypsela is yellow and conspicuous.

Tall thistle (Cirsium altissimum) leaves are shallowly lobed, the lobes cut less than of the way to the midrib.


Dry to moderate moisture. Prairies, fields, forest openings, river bottoms, roadsides, disturbed areas. Full sun.




July to October


Pests and Diseases






Distribution Map



2, 3, 4, 5, 7, 22, 24, 28, 30.









  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Asterales (sunflowers, bellflowers, fanflowers, and allies)  


Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Carduoideae (thistles and allies)  
  Tribe Cardueae  
  Subtribe Carduinae (thistles and burdocks)  
  Genus Cirsium (plume thistles)  

Cardueae is a synonym of the tribe name. Cynareae was published first and has precedence. Nevertheless, most sources use the name Cardueae for the tribe.


Subordinate Taxa






Carduus discolor


Common Names


field thistle

pasture thistle












A dry, one-chambered, single-seeded seed capsule, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.



Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.



A whorl of bracts beneath or surrounding a flower or flower cluster.



The stalk of a single flower or flower cluster.



Deeply cut, more than half way to the midrib but not to the midrib, into lobes that are spaced out along the midrib; the lobes do not form separate leaflets.



Densely covered with short, soft, matted or tangled, woolly, usually white or silvery hairs.



A thin, flat, membranous, usually transparent appendage on the margin of a structure.

The Native Thistle Test

Thistles native to Minnesota do not have spiny stems. Grasp the stem near the base of any native thistle loosely in your fist, then slide your fist upwards to just below the inflorescence. If the plant is a native thistle, you will not get a single prickle – it will be “ouchless”.

If the thistle in question is thought to be an exotic (non-native) species, this test is not recommended.

Field thistle is native.


Visitor Photos

Share your photo of this plant.

  This button not working for you?
Simply email us at
Attach one or more photos and, if you like, a caption.


    field thistle   field thistle  
    field thistle      


    field thistle   field thistle  
    field thistle   field thistle  
    field thistle      


    field thistle   field thistle  
    field thistle      

Flower Head

    field thistle   field thistle  
    field thistle   field thistle  
    field thistle      


    field thistle   field thistle  
    field thistle      


    field thistle   field thistle  

Leaf upper side

    field thistle   field thistle  

Leaf underside

    field thistle      


    field thistle   field thistle  
    field thistle      



  Cirsium discolor (Pasture Thistle)
Allen Chartier
  Cirsium discolor (Pasture Thistle)  
  Cirsium discolor PASTURE THISTLE
Frank Mayfield
  Cirsium discolor PASTURE THISTLE  



Visitor Videos

Share your video of this plant.

  This button not working for you?
Simply email us at
Attach a video, a YouTube link, or a cloud storage link.


Other Videos
  Georgia State Undergraduate Reseach Conference - Thistle
Georgia State University

Published on Apr 8, 2014

These undergrads are among nearly 150 students whose work will be highlighted at the Georgia State Undergraduate Research Conference on Thursday, April 10 at the University Center. Students will share their findings through oral presentations, posters, artistic displays, and performances. The event is free and open to the public.


Year: Seniors

Major: Biology, College of Arts and Sciences

Title of Research Project: "Antimicrobial Activity of Cirsium discolor Flower Extract against Staphylococcus aureus and Acinetobacter baummannii"

The Project:
When it comes to fighting bacterial infections, modern medicine is starting to lose the war. Bacteria are becoming increasingly resistant to every antibiotic that's in a doctor's arsenal, and scientists are working to find new ways to fight infections as the old medicines fail.

Allen, Graell and Pujada looked to see if Cirsium discolor, a type of field thistle, could fight two different bacteria. One, Staphylococcus aureus is the source of staph infections that can cause numerous diseases: pneumonia, heart failure and severe bone inflammation. Acinetobacter baummannii is a stubborn organism that often makes its home in hospitals, causing infections that are incredibly difficult to treat with existing antibiotics.

While this particular thistle is known to help lower blood pressure, scientists have never investigated whether it could fight bacteria -- until now. Through their research, this undergraduate team found that there is a chemical compound in the thistle's extract that fights both species of bacteria.

Choosing the Research Subject:
For Pujada, the possibility of new discoveries in medicine in nature was exciting. She, Allen and Graell took a class on medicinal plants, taught by their research faculty sponsor, Maria Nagy.

"I liked the idea of picking out our own plants, then going back to use those plants to help find new antibiotics," she said.

Fun Fact:
When not busy in the lab, Allen likes to try her hand in the kitchen.

"I enjoy Cake Boss and shows like that, and I play and mimic like I'm on the show," she said. "I have my family members try out the disasters -- and sometimes they taste good, sometimes not so much."




Visitor Sightings

Report a sighting of this plant.

  This button not working for you?
Simply email us at
Be sure to include a location.

Location: Fairview Twp, Cass County

field thistle  

Baker Park Reserve

Bertram Chain of Lakes Regional Park

Big Woods Heritage Forest WMA

Blaine Preserve SNA

Blanket Flower Prairie SNA

Bur Oak WMA

Camden State Park

Carpenter St. Croix Valley Nature Center

Carver Highlands WMA, South Unit

Charles A. Lindbergh State Park

Cherry Grove Blind Valley SNA

Chippewa Prairie

Compass Prairie SNA

Cottonwood River Prairie SNA

Crow-Hassan Park Reserve

Falls Creek SNA

Flandrau State Park

Forestville/Mystery Cave State Park

Frontenac State Park

Glacial Lakes State Park

Hardscrabble Woods / MG Tusler Sanctuary

Hastings Sand Coulee SNA

Hyland Lake Park Reserve

Hythecker Prairie SNA

Iron Horse Prairie SNA

Jensen Memorial WMA

John Murtaugh Memorial WMA

John Peter Hoffman Spring Brook Valley WMA

Kasota Prairie

Kasota Prairie SNA

Kettledrummer Prairie

Kilen Woods State Park

Lake Byllesby Regional Park

Lake Elmo Park Reserve

Lake Louise State Park

Lebanon Hills Regional Park

Lost Valley Prairie SNA

Minnesota Valley NWR, Wilkie Unit

Mound Prairie SNA

Murphy-Hanrehan Park Reserve

Myre-Big Island State Park

Oronoco Prairie SNA

Osmundson Prairie SNA

Otter Tail Prairie SNA

Pilot Knob

Pin Oak Prairie SNA

Plover Prairie, East Unit

Prairie Bush Clover SNA

Prairie Coteau SNA

Prairie Creek WMA, Koester Prairie Unit

Racine Prairie SNA

Red Rock Prairie

Regal Meadow

Rice Lake State Park

Ritter Farm Park

River Terrace Prairie SNA

Rockville County Park

St. Croix Savanna SNA

Sandpiper Prairie SNA

Savage Fen SNA

Seven Springs WMA

Shooting Star Prairie SNA

Sibley State Park

Springbrook Nature Center

Staffanson Prairie

Swedes Forest SNA

Tiedemann WMA

Vermillion River WMA

Whitetail Woods Regional Park

Whitewater State Park

Wild Indigo SNA

Woodbury WMA

Woodland Trails Regional Park







Last Updated:

© All rights reserved.

About Us

Privacy Policy

Contact Us