Bloomipedia
Green antelopehorns (Asclepias viridis)
Photo: evangrimes via iNaturalist · CC BY 4.0 · resized

Flower profile

Green antelopehorns

Asclepias viridis

Green antelopehorns (Asclepias viridis) is a flowering plant in the Apocynaceae family, native in the lower 48 states, blooming mostly April–June across the U.S.

Native in the lower 48

Green antelopehorns 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 April–June.

18states where USDA records it
5Bloomipedia state lists include it
29,538U.S. sightings*

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

On our lists for: Arkansas, Kansas, Mississippi, Oklahoma, Texas

Quick look

Asclepias viridis is a species of milkweed, a plant in the dogbane family known by the common names green milkweed, green antelopehorn and spider milkweed. The Latin word viridis means green. The plant is native to the midwestern, south central and southeastern United States, as well as to the southeastern portion of the western United States.

  • It belongs to the Apocynaceae family. iNaturalist
  • USDA PLANTS describes it as an herb (forb) with a perennial life cycle. USDA PLANTS
  • USDA PLANTS lists it as native in the lower 48 states and records it in 18 states. USDA PLANTS
  • NatureServe lists it as native to Texas, Oklahoma, Kansas, Arkansas and Mississippi. NatureServe
  • In Texas, most iNaturalist sightings of it in flower come in April–May. iNaturalist
  • In Oklahoma, most iNaturalist sightings of it in flower come in April–June. iNaturalist
  • iNaturalist has 21,579 research-grade sightings of it in Texas, ranking #13 among the 169 flowers on our Texas list. iNaturalist
  • iNaturalist has 2,703 research-grade sightings of it in Oklahoma, ranking #1 among the 159 flowers on our Oklahoma list. iNaturalist
  • iNaturalist has 1,683 research-grade sightings of it in Kansas, ranking #1 among the 151 flowers on our Kansas list. iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (4,136 records)
Bloom time in the 5 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
TexasNativeApril–May21,579
OklahomaNativeApril–June2,703
KansasNativeMay–June1,683
ArkansasNativeApril–July727
MississippiNativeApril–May444

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
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
Oklahoma
No list Oklahoma has no state law listing endangered or threatened plants, so we show NatureServe's Oklahoma ranks instead. NatureServe: SNR, not yet ranked in Oklahoma.
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.
Arkansas
No list Arkansas has no state law listing endangered or threatened plants, so we show NatureServe's Arkansas ranks instead. NatureServe: SNR, not yet ranked in Arkansas.
Mississippi
No list Mississippi has no state law listing endangered or threatened plants, so we show NatureServe's Mississippi ranks instead. NatureServe: SNR, not yet ranked in Mississippi.
Rare elsewhere
Other states where NatureServe ranks it rare or missing: IN (S1), SC (SX), WV (SH). (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 peoplePoisonous to people

NC State Extension lists it as poisonous to humans (severity: low). Poisonous parts: flowers, leaves, stems. Symptoms they list: “Can cause stomach upset, nausea, vomiting, abdominal pain, diarrhea, weakness, lethargy, and confusion if eaten in quantity. Milky sap can cause contact dermatitis and eye irritation.” NC State Extension

For petsToxic to dogs, cats and horses

ASPCA's entry “Milkweed” (Asclepias species), which covers the whole genus, lists it as toxic to dogs, cats and horses. Signs include: Vomiting, profound depression, weakness, anorexia, and diarrhea are common; may be followed by seizures, difficulty breathing, rapid, weak pulse, dilated pupils, kidney or liver failure, coma… 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 green antelopehorns in 18 states.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, Ohio, Oklahoma, South Carolina, Tennessee, Texas, West Virginia.

Texas counties with USDA records: Aransas, Bastrop, Brazoria, Brazos, Burleson, Caldwell, Calhoun, Chambers, Clay, Collin, Comal, Cooke, Dallas, Denton, Ellis, Fannin, Fayette, Fort Bend, Freestone, Galveston, Gillespie, Gonzales, Grayson, Grimes, Harris, Hays, Hill, Hopkins, Hunt, Jackson, Jefferson, Jim Wells, Johnson, Kaufman, Kendall, Kerr, Lamar, Lampasas, Lavaca, Leon, Matagorda, McLennan, Montgomery, Navarro, Newton, Polk, Red River, Refugio, Sabine, San Jacinto, Tarrant, Titus, Travis, Tyler, Van Zandt, Victoria, Walker, Washington, Wharton, Wichita, Williamson, Wise, Wood.

Oklahoma counties with USDA records: Blaine, Bryan, Caddo, Carter, Cherokee, Choctaw, Comanche, Cotton, Creek, Custer, Garfield, Grady, Grant, Haskell, Jefferson, Johnston, Kay, Latimer, Le Flore, Logan, Marshall, McClain, Murray, Muskogee, Okfuskee, Oklahoma, Osage, Ottawa, Payne, Pontotoc, Pottawatomie, Rogers, Sequoyah, Tulsa, Washington, Woods.

Kansas counties with USDA records: Allen, Anderson, Atchison, Barber, Barton, Bourbon, Brown, Butler, Chase, Chautauqua, Cherokee, Clark, Clay, Cloud, Coffey, Comanche, Cowley, Crawford, Dickinson, Douglas, Edwards, Elk, Ellis, Ellsworth, Franklin, Greenwood, Harper, Harvey, Jackson, Jefferson, Jewell, Johnson, Kingman, Kiowa, Labette, Leavenworth, Lincoln, Linn, Logan, Lyon, Marion, Marshall, McPherson, Miami, Mitchell, Montgomery, Morris, Nemaha, Neosho, Osage, Osborne, Ottawa, Pawnee, Pottawatomie, Pratt, Reno, Republic, Rice, Riley, Rush, Russell, Saline, Sedgwick, Shawnee, Stafford, Sumner, Wabaunsee, Washington, Wilson, Woodson, Wyandotte.

Names, range and relatives

Other scientific names (synonyms in USDA PLANTS): Asclepiodora viridis.

County records: USDA PLANTS lists it in 387 counties across 16 states; the most are in Kansas (71), Texas (63), Missouri (54).

Other Asclepias on Bloomipedia (16): Common milkweed, Butterfly milkweed, Swamp milkweed, Antelopehorn milkweed, Showy milkweed, Narrowleaf milkweed, Green comet milkweed, Zizotes milkweed, Tropical milkweed, Redring milkweed.

More from the Apocynaceae family (28 on Bloomipedia; most observed first): Lesser periwinkle, Greater periwinkle, Spreading dogbane, Pearl milkweed, Madagascar periwinkle, Honey-vine climbing milkweed, Hartweg's climbing milkweed, Oleander.

More Texas flowers

Antelopehorn milkweed (Asclepias asperula)

Antelopehorn milkweed

Asclepias asperula

Native

🌼 Blooms in TX: April–May
Zizotes milkweed (Asclepias oenotheroides)

Zizotes milkweed

Asclepias oenotheroides

Native

🌼 Blooms in TX: April–September
Pearl milkweed (Matelea reticulata)

Pearl milkweed

Matelea reticulata

Native

🌼 Blooms in TX: April–June

Sources