Bloomipedia
Crossflower (Chorispora tenella)
Photo: Jared Lincenberg via iNaturalist · CC BY 4.0 · resized

Flower profile

Crossflower

Chorispora tenella

Crossflower (Chorispora tenella) is a flowering plant in the Brassicaceae family, introduced in the lower 48 states, blooming mostly March–May across the U.S.

Introduced in the lower 48

Crossflower is a wildflower that USDA PLANTS lists as introduced in the lower 48 states. It's on our flower lists for 4 states, and across the U.S. it's most often seen in bloom in March–May.

31states where USDA records it
4Bloomipedia state lists include it
7,795U.S. sightings*

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

On our lists for: Colorado, Idaho, Nevada, Utah

Quick look

Chorispora tenella is a species of flowering plant in the mustard family known by several common names, including purple mustard, blue mustard, musk mustard, and crossflower. This mustard is native to parts of Eurasia but is well known in other parts of the world, particularly in temperate regions, as an introduced species and a noxious weed.

  • It belongs to the Brassicaceae family. iNaturalist
  • USDA PLANTS describes it as an herb (forb) with a annual life cycle. USDA PLANTS
  • USDA PLANTS lists it as introduced in the lower 48 states and records it in 31 states. USDA PLANTS
  • NatureServe lists it as not native to Colorado, Utah, Idaho and Nevada. NatureServe
  • In Colorado, most iNaturalist sightings of it in flower come in March–June. iNaturalist
  • In Utah, most iNaturalist sightings of it in flower come in March–May. iNaturalist
  • iNaturalist has 2,662 research-grade sightings of it in Colorado, ranking #55 among the 160 flowers on our Colorado list. iNaturalist
  • iNaturalist has 1,326 research-grade sightings of it in Utah, ranking #36 among the 153 flowers on our Utah list. iNaturalist
  • iNaturalist has 739 research-grade sightings of it in Idaho, ranking #35 among the 143 flowers on our Idaho list. iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (798 records)
Bloom time in the 4 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
ColoradoIntroducedMarch–June2,662
UtahIntroducedMarch–May1,326
IdahoIntroducedfew records (41)739
NevadaIntroducedfew records (40)458

Conservation status

Federal (U.S. ESA)
Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
NatureServe global
GNR Not yet ranked worldwide. NatureServe
Colorado
No list Colorado has no state law listing endangered or threatened plants, so we show NatureServe's Colorado ranks instead. NatureServe: SNA, not applicable (usually because it isn't native there) in Colorado.
Utah
No list Utah has no state law listing endangered or threatened plants, so we show NatureServe's Utah ranks instead. NatureServe: SNA, not applicable (usually because it isn't native there) in Utah.
Idaho
No list Idaho has no state law listing endangered or threatened plants, so we show NatureServe's Idaho ranks instead. NatureServe: SNA, not applicable (usually because it isn't native there) in Idaho.
Nevada
Not listed Not on Nevada fully protected plants, critically endangered (NAC 527.010). NatureServe: SNA, not applicable (usually because it isn't native there) in Nevada. NAC 527.010
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 peopleNot well documented

None of the sources we checked (NC State Extension (no page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.

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 crossflower in 31 states.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, Arkansas, California, Colorado, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Washington, West Virginia, Wyoming.

Colorado counties with USDA records: Arapahoe, Baca, Boulder, Cheyenne, Custer, El Paso, Elbert, Jefferson, Kiowa, La Plata, Larimer, Las Animas, Lincoln, Logan, Mesa, Moffat, Montezuma, Montrose, Otero, Pueblo, Rio Blanco, Sedgwick, Summit.

Utah counties with USDA records: Beaver, Box Elder, Cache, Carbon, Daggett, Davis, Duchesne, Emery, Garfield, Grand, Iron, Juab, Kane, Millard, Morgan, Piute, Rich, Salt Lake, San Juan, Sanpete, Sevier, Summit, Tooele, Uintah, Utah, Wasatch, Washington, Wayne, Weber.

Idaho counties with USDA records: Ada, Bannock, Bingham, Blaine, Canyon, Caribou, Cassia, Elmore, Fremont, Gem, Idaho, Jerome, Lincoln, Nez Perce, Owyhee, Payette, Power, Twin Falls, Washington.

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Waif (occasional, not established); Lower 48 states: Introduced.

County records: USDA PLANTS lists it in 287 counties across 29 states; the most are in Montana (35), Kansas (31), Utah (29).

More from the Brassicaceae family (24 on Bloomipedia; most observed first): Garlic mustard, Dame's rocket, Cut-leaved toothwort, Wild radish, Milkmaids, Annual honesty, Western wallflower, Hoary alyssum.

More Colorado flowers

Western wallflower (Erysimum capitatum)

Western wallflower

Erysimum capitatum

Native

🌼 Blooms in CO: May–July
Fendler's pennycress (Noccaea fendleri)

Fendler's pennycress

Noccaea fendleri

Native

🌼 Blooms in CO: May–July
Hoary alyssum (Berteroa incana)

Hoary alyssum

Berteroa incana

Introduced

🌼 Blooms in CO: June–September

Sources