Flower profile

Buffalo-bur

Solanum rostratum

Buffalo-bur (Solanum rostratum) is a flowering plant in the Solanaceae family, native in the lower 48 states, blooming mostly June–September across the U.S.

Native in the lower 48

Buffalo-bur is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 5 states, and across the U.S. it's most often seen in bloom in June–September.

47states where USDA records it

5Bloomipedia state lists include it

15,962U.S. sightings*

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

On our lists for: Kansas, Nebraska, North Dakota, South Dakota, Texas

Quick look

Solanum rostratum is a species of nightshade that is native to the United States and northern and central Mexico. Common names include buffalobur nightshade, buffalo-bur, spiny nightshade, Colorado bur, Kansas thistle, bad woman, Mexican thistle, and Texas thistle.
From Wikipedia's article Solanum rostratum, CC BY-SA 4.0.

It belongs to the Solanaceae family. ^iNaturalist
USDA PLANTS describes it as an herb (forb) with a annual life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 47 states. ^{USDA PLANTS}
NatureServe lists it as native to Texas, Kansas, Nebraska, South Dakota and North Dakota. ^NatureServe
In Texas, most iNaturalist sightings of it in flower come in June–September. ^iNaturalist
iNaturalist has 9,168 research-grade sightings of it in Texas, ranking #63 among the 169 flowers on our Texas list. ^iNaturalist
iNaturalist has 740 research-grade sightings of it in Kansas, ranking #23 among the 151 flowers on our Kansas list. ^iNaturalist
iNaturalist has 406 research-grade sightings of it in Nebraska, ranking #23 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”) (1,154 records)

Bloom time in the 5 states whose Bloomipedia list includes it

State	Type	Peak bloom	Sightings*
Texas	Native	June–September	9,168
Kansas	Native	few records (37)	740
Nebraska	Native	few records (25)	406
South Dakota	Native	few records (26)	316
North Dakota	Native	few records (6)	75

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
Texas: Not listed Not on Texas endangered and threatened plants (31 Tex. Admin. Code § 69.8), as listed by Texas Parks and Wildlife. NatureServe: SNR, not yet ranked in Texas. ^{31 TAC 69.8}
Kansas: No list Kansas's endangered and threatened list (K.A.R. 115-15-1) covers animals only, so we show NatureServe's Kansas ranks for plants. NatureServe: S5, secure in Kansas.
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}
South Dakota: No list South Dakota's endangered and threatened list (ARSD 41:10:02) covers animals only, so we show NatureServe's South Dakota ranks for plants. NatureServe: SNR, not yet ranked in South Dakota.
North Dakota: No list North Dakota has no state law listing endangered or threatened plants, so we show NatureServe's North Dakota ranks instead. NatureServe: SNR, not yet ranked in North Dakota.
Rare elsewhere: Other states where NatureServe ranks it rare or missing: NV (S2). (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 page for this plant), USDA PLANTS) say whether it's edible or poisonous for people.

For petsToxic to dogs, cats and horses

ASPCA's entry “Deadly Nightshade” (Solanum spp), which covers the whole genus, lists it as toxic to dogs, cats and horses. Signs include: Hypersalivation, inappetence, severe gastrointestinal upset, diarrhea, drowsiness, CNS depression, confusion, behavioral change, weakness, dilated pupils, slow heart… ^ASPCA

🌿 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 buffalo-bur in 47 states plus Washington, D.C.

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recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming; District of Columbia.

Texas counties with USDA records: Andrews, Aransas, Archer, Bailey, Bandera, Bastrop, Bell, Bexar, Blanco, Brazos, Brewster, Briscoe, Brown, Burnet, Cameron, Carson, Castro, Childress, Coleman, Comal, Comanche, Concho, Cooke, Coryell, Cottle, Crockett, Culberson, Dallam, Dallas, Deaf Smith, Denton, Dickens, Donley, Eastland, Edwards, Ellis, Erath, Fayette, Floyd, Garza, Gillespie, Gonzales, Gray, Grayson, Gregg, Grimes, Hale, Hall, Hansford, Hardeman, Harris, Hartley, Hays, Hemphill, Hill, Hockley, Hutchinson, Jeff Davis, Karnes, Lamb, Lampasas, Lee, Leon, Lipscomb, Lubbock, Marion, McLennan, Menard, Mills, Mitchell, Moore, Motley, Nolan, Ochiltree, Oldham, Parker, Parmer, Pecos, Potter, Presidio, Randall, Reeves, Roberts, Robertson, Shackelford, Sherman, Starr, Sutton, Swisher, Tarrant, Terrell, Titus, Tom Green, Travis, Val Verde, Walker, Washington, Webb, Wheeler, Wichita, Williamson, Wood, Yoakum.

Kansas counties with USDA records: Allen, Anderson, Atchison, Barber, Barton, Bourbon, Brown, Butler, Chase, Chautauqua, Cherokee, Cheyenne, Clark, Clay, Cloud, Coffey, Comanche, Cowley, Crawford, Decatur, Dickinson, Doniphan, Douglas, Edwards, Elk, Ellis, Ellsworth, Finney, Ford, Franklin, Geary, Gove, Graham, Grant, Gray, Greeley, Greenwood, Hamilton, Harper, Harvey, Haskell, Hodgeman, Jackson, Jefferson, Jewell, Johnson, Kearny, Kingman, Kiowa, Labette, Lane, Leavenworth, Lincoln, Linn, Logan, Lyon, Marion, Marshall, McPherson, Meade, Miami, Mitchell, Montgomery, Morris, Morton, Nemaha, Neosho, Ness, Norton, Osage, Osborne, Ottawa, Pawnee, Phillips, Pottawatomie, Pratt, Rawlins, Reno, Republic, Rice, Riley, Rooks, Rush, Russell, Saline, Scott, Sedgwick, Seward, Shawnee, Sheridan, Sherman, Smith, Stafford, Stanton, Stevens, Sumner, Thomas, Trego, Wabaunsee, Wallace, Washington, Wichita, Wilson, Woodson, Wyandotte.

Nebraska counties with USDA records: Banner, Boone, Box Butte, Buffalo, Cass, Chase, Cherry, Cuming, Dakota, Dawes, Dawson, Deuel, Dixon, Dodge, Douglas, Dundy, Franklin, Frontier, Furnas, Gage, Garden, Hall, Harlan, Howard, Jefferson, Kearney, Keith, Keya Paha, Lancaster, Lincoln, Merrick, Morrill, Nemaha, Nuckolls, Otoe, Phelps, Platte, Red Willow, Richardson, Saunders, Scotts Bluff, Sheridan, Sherman, Sioux, Thayer, Thomas, Washington, Webster.

Names, range and relatives

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

Other scientific names (synonyms in USDA PLANTS): Androcera rostrata.

County records: USDA PLANTS lists it in 937 counties across 44 states; the most are in Kansas (105), Texas (103), Missouri (72).

Other Solanum on Bloomipedia (6): Carolina horsenettle, Bittersweet nightshade, Silverleaf nightshade, Eastern black nightshade, Western horsenettle, American black nightshade.

More from the Solanaceae family (15 on Bloomipedia; most observed first): Sacred datura, Tree tobacco, Jimsonweed, Desert tobacco, Long-leaved groundcherry, Thickleaf groundcherry, Cutleaf groundcherry, Desert thorn-apple.

More Texas flowers

Silverleaf nightshade

Solanum elaeagnifolium

Native

🌼 Blooms in TX: April–September

Western horsenettle

Solanum dimidiatum

Native

🌼 Blooms in TX: April–June

Pinkladies

Oenothera speciosa

Native

🌼 Blooms in TX: March–May

Sources

USDA, NRCS. PLANTS Database, profile SORO.
iNaturalist, Solanum rostratum: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Solanum rostratum (lead quoted under CC BY-SA 4.0).
Texas: Texas endangered and threatened plants (31 Tex. Admin. Code § 69.8), as listed by Texas Parks and Wildlife.
Texas: Texas noxious and invasive plant list (4 Tex. Admin. Code § 19.300(a)).
Kansas: Kansas noxious weeds (K.A.R. 4-8-44, as amended 2026).
Nebraska: Nebraska threatened and endangered species (163 Neb. Admin. Code ch. 4, § 004).
Nebraska: Nebraska noxious weeds (25 Neb. Admin. Code ch. 10, § 001.02).
South Dakota: South Dakota statewide noxious weeds (ARSD 12:62:03:01.06).
North Dakota: North Dakota state noxious weeds (N.D. Admin. Code 7-06-01-02), as listed by the ND Department of Agriculture.
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Solanum rostratum (global and state ranks).
Edibility and toxicity: ASPCA.
Photo: Michelle W. （鍾偉瑋） via iNaturalist · CC BY 4.0 · resized.