Bloomipedia
Thistle poppy (Argemone polyanthemos)
Photo: Tyler via iNaturalist · CC0 · resized

Flower profile

Thistle poppy

Argemone polyanthemos

Thistle poppy (Argemone polyanthemos) is a flowering plant in the Papaveraceae family, native in the lower 48 states, blooming mostly June–August across the U.S.

Native in the lower 48

Thistle poppy 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 June–August.

16states where USDA records it
2Bloomipedia state lists include it
4,648U.S. sightings*

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

On our lists for: Colorado, Nebraska

Quick look

Argemone polyanthemos, the crested pricklypoppy, also known as bluestem prickly poppy, pricklypoppy, white prickly poppy, annual pricklypoppy, or as thistle poppy is an annual plant with yellow sap and showy white flowers in the poppy family (Papaveraceae).

  • It belongs to the Papaveraceae family. iNaturalist
  • USDA PLANTS describes it as an herb (forb) with a annual, biennial, perennial life cycle. USDA PLANTS
  • USDA PLANTS lists it as native in the lower 48 states and records it in 16 states. USDA PLANTS
  • NatureServe lists it as native to Colorado and Nebraska. NatureServe
  • In Colorado, most iNaturalist sightings of it in flower come in June–August. iNaturalist
  • USDA PLANTS lists its flower color as white. USDA PLANTS
  • USDA PLANTS gives its bloom period as mid spring. USDA PLANTS
  • USDA PLANTS lists a mature height of about 3 ft. USDA PLANTS
  • iNaturalist has 3,461 research-grade sightings of it in Colorado, ranking #39 among the 160 flowers on our Colorado list. iNaturalist
  • iNaturalist has 445 research-grade sightings of it in Nebraska, ranking #16 among the 147 flowers on our Nebraska list. iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (261 records)
Bloom time in the 2 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
ColoradoNativeJune–August3,461
NebraskaNativefew records (20)445

Conservation status

Federal (U.S. ESA)
Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
NatureServe global
G4 Apparently secure worldwide. NatureServe
Colorado
No list Colorado has no state law listing endangered or threatened plants, so we show NatureServe's Colorado ranks instead. NatureServe: S4, apparently secure in Colorado.
Nebraska
Not listed Not on Nebraska threatened and endangered species (163 Neb. Admin. Code ch. 4, § 004). NatureServe: SNR, not yet ranked in Nebraska. 163 NAC 4-004
Rare elsewhere
No other U.S. state ranks it S1, S2, SH or SX.

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

Can you eat it?

For peopleToxic (moderate, per USDA)

USDA PLANTS rates its toxicity as “moderate.” (USDA's rating covers people and livestock and doesn't say which parts.) NC State Extension has no page for it. USDA PLANTS

For petsNot well documented

It isn't on the ASPCA plant list.

🌿 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 thistle poppy in 16 states.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Colorado, Idaho, Illinois, Indiana, Iowa, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, Washington, Wyoming.

Colorado counties with USDA records: Baca, Boulder, Cheyenne, Clear Creek, Denver, El Paso, Elbert, Gilpin, Huerfano, Jefferson, Kiowa, Kit Carson, Larimer, Las Animas, Lincoln, Logan, Montezuma, Morgan, Otero, Phillips, Sedgwick, Washington, Weld, Yuma.

Nebraska counties with USDA records: Arthur, Banner, Box Butte, Boyd, Brown, Buffalo, Chase, Cherry, Cuming, Custer, Dawes, Dawson, Deuel, Dundy, Franklin, Frontier, Furnas, Gage, Garden, Grant, Hall, Harlan, Hitchcock, Holt, Hooker, Jefferson, Kearney, Knox, Lincoln, Logan, McPherson, Morrill, Perkins, Red Willow, Scotts Bluff, Sheridan, Sioux, Thomas, Webster.

Growing conditions

USDA PLANTS gives Thistle poppy a high shade tolerance, high drought tolerance and low moisture use. It is rated for soil pH 7.0 to 8.5 and winter lows down to -23 °F.

Shade tolerance
High
Drought tolerance
High
Moisture use
Low
Soil textures it is adapted to
coarse, medium
Soil pH range
7.0 to 8.5
Minimum temperature tolerated
-23 °F
Frost-free days needed (minimum)
140
Annual precipitation range
10 to 15 inches
Minimum root depth
6 inches
Salinity tolerance
Low
Fertility requirement
Low
Growth rate
Rapid
Lifespan
Long
Active growth period
Summer
Fruit or seed
· Summer to Fall
Can be propagated by
seed
Commercial availability
No Known Source

From the USDA PLANTS characteristics data for ARPO2. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

County records: USDA PLANTS lists it in 213 counties across 10 states; the most are in Kansas (64), Texas (43), Nebraska (39).

Other Argemone on Bloomipedia (3): Flatbud prickly poppy, Southwestern prickly poppy, Pua kala.

More from the Papaveraceae family (16 on Bloomipedia; most observed first): Bloodroot, California poppy, Dutchman's breeches, Greater celandine, Pacific bleeding heart, Celandine poppy, Bush poppy, Squirrel corn.

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Sources