Bloomipedia
Field thistle (Cirsium discolor)
Photo: Elizabeth Green via iNaturalist · CC BY 4.0 · resized

Flower profile

Field thistle

Cirsium discolor

Field thistle (Cirsium discolor) is a flowering plant in the Asteraceae family, native in the lower 48 states, blooming mostly August–September across the U.S.

Native in the lower 48

Field thistle is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 2 states, and across the U.S. it's most often seen in bloom in August–September.

33states where USDA records it
2Bloomipedia state lists include it
10,733U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Iowa, Maryland

Quick look

Cirsium discolor, the field thistle, is a North American species of plants in the tribe Cardueae within the family Asteraceae. It is native to thirty-three states in the United States as well four Canadian provinces. It occurs across much of eastern and central Canada as well as eastern and central United States. It has been found from New Brunswick west to Saskatchewan and south as far as Texas and Georgia.

  • It belongs to the Asteraceae family. iNaturalist
  • USDA PLANTS describes it as an herb (forb) with a biennial, perennial life cycle. USDA PLANTS
  • USDA PLANTS lists it as native in the lower 48 states and records it in 33 states. USDA PLANTS
  • NatureServe lists it as native to Maryland and Iowa. NatureServe
  • In Maryland, most iNaturalist sightings of it in flower come in August–September. iNaturalist
  • iNaturalist has 1,144 research-grade sightings of it in Maryland, ranking #101 among the 189 flowers on our Maryland list. iNaturalist
  • iNaturalist has 263 research-grade sightings of it in Iowa, ranking #101 among the 147 flowers on our Iowa list. iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (1,329 records)
Bloom time in the 2 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
MarylandNativeAugust–September1,144
IowaNativefew records (15)263

Conservation status

Federal (U.S. ESA)
Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
NatureServe global
G5 Secure worldwide. NatureServe
Maryland
Not listed Not on Maryland threatened and endangered plants (COMAR 08.03.08.05, .06 and .08). NatureServe: SNR, not yet ranked in Maryland. COMAR 08.03.08
Iowa
Not listed Not on Iowa endangered, threatened and special concern plants (Iowa Admin. Code r. 571-77.3). NatureServe: S5, secure in Iowa. IAC 571-77.3
Rare elsewhere
Other states where NatureServe ranks it rare or missing: NE (S1), SC (S1), VT (S1). (S1 critically imperiled, S2 imperiled, SH possibly extirpated, SX presumed extirpated.)

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleNot well documented

None of the sources we checked (NC State Extension (no edibility or poison notes on its page), USDA PLANTS) say whether it's edible or poisonous for people. NC State Extension

For petsNot well documented

It isn't on the ASPCA plant list, and NC State Extension doesn't flag it for pets.

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records field thistle in 33 states plus Washington, D.C.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alabama, Arkansas, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, Wisconsin; District of Columbia.

Iowa counties with USDA records: Cherokee, Guthrie, Lyon, Madison, Sioux.

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Native; Lower 48 states: Native.

Other scientific names (synonyms in USDA PLANTS): Carduus discolor.

County records: USDA PLANTS lists it in 711 counties across 31 states; the most are in Illinois (100), Virginia (77), Kentucky (59).

Other Cirsium on Bloomipedia (12): Bull thistle, Creeping thistle, Bristle thistle, Cobwebby thistle, Texas thistle, Wavyleaf thistle, Tall thistle, Elk thistle, New Mexico thistle, Pitcher's thistle.

More from the Asteraceae family (212 on Bloomipedia; most observed first): Common yarrow, Goldenrods, White snakeroot, Sunflowers, Chicory, Black-eyed Susan, Common dandelion, Firewheel.

More Maryland flowers

Chicory (Cichorium intybus)

Chicory

Cichorium intybus

Introduced

🌼 Blooms in MD: June–September
Late boneset (Eupatorium serotinum)

Late boneset

Eupatorium serotinum

Native

🌼 Blooms in MD: August–October
Wingstem (Verbesina alternifolia)

Wingstem

Verbesina alternifolia

Native

🌼 Blooms in MD: August–September

Sources