Bloomipedia
Butterfly milkweed (Asclepias tuberosa)
Photo: Lynn Harper via iNaturalist · CC0 · resized

Flower profile

Butterfly milkweed

Asclepias tuberosa

Butterfly milkweed (Asclepias tuberosa) is a flowering plant in the Apocynaceae family, native in the lower 48 states, blooming mostly May–August across the U.S.

Native in the lower 48

Butterfly milkweed is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 28 states, and across the U.S. it's most often seen in bloom in May–August.

41states where USDA records it
28Bloomipedia state lists include it
62,599U.S. sightings*

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

On our lists for: Alabama, Arkansas, Connecticut, Delaware, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, West Virginia, Wisconsin

Quick look

Asclepias tuberosa, commonly known as butterfly weed or pleurisy root, is a species of milkweed native to eastern and southwestern North America. It is commonly known as butterfly weed because of the butterflies that are attracted to the plant by its color and its copious production of nectar.

  • 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 41 states. USDA PLANTS
  • In Illinois, most iNaturalist sightings of it in flower come in June–August. iNaturalist
  • In New York, most iNaturalist sightings of it in flower come in June–August. iNaturalist
  • USDA PLANTS lists its flower color as orange. USDA PLANTS
  • USDA PLANTS gives its bloom period as mid summer. USDA PLANTS
  • USDA PLANTS lists a mature height of about 2 ft. USDA PLANTS
  • iNaturalist has 4,537 research-grade sightings of it in Illinois, ranking #23 among the 180 flowers on our Illinois list. iNaturalist
  • iNaturalist has 4,334 research-grade sightings of it in New York, ranking #51 among the 193 flowers on our New York list. iNaturalist
  • iNaturalist has 3,731 research-grade sightings of it in Wisconsin, ranking #24 among the 161 flowers on our Wisconsin list. iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (10,767 records)
Bloom time in the 28 states whose Bloomipedia list includes it
StateTypePeak bloomSightings*
IllinoisNativeJune–August4,537
New YorkNativeJune–August4,334
WisconsinNativeJune–August3,731
MinnesotaNativeJune–August3,372
OhioNativeJune–August3,329
North CarolinaNativeMay–July2,890
MichiganNativeJune–August2,853
PennsylvaniaNativeJune–August2,749
VirginiaNativeJune–August2,427
TennesseeNativeMay–August2,326
MassachusettsNativeJune–August2,041
GeorgiaNativeMay–July2,001
IndianaNativeJune–July1,774
MissouriNativeMay–July1,751
MarylandNativeJune–July1,669
New JerseyNativeJune–August1,580
IowaNativeJune–August1,272
KansasNativeMay–June1,230
AlabamaNativeMay–July1,189
ArkansasNativeMay–July1,105
KentuckyNativeJune–July995
South CarolinaNativeMay–July934
OklahomaNativeMay–June883
ConnecticutNativeJune–August631
West VirginiaNativeJune–August521
MississippiNativeMay–July461
DelawareNativeJune–August239
Rhode IslandNativeJune–August156

Conservation status

Federal (U.S. ESA)
Not listed Not listed under the Endangered Species Act. USFWS ECOS does track it with the label “Not Listed,” which is informal and gives no legal protection. USFWS ECOS
NatureServe global
G5 Secure worldwide. NatureServe
State rare plant lists
Not listed Not on the official rare plant list in 19 of our 28 states.
See each state
Illinois
Not listed Not on Illinois List of Endangered and Threatened Flora (17 Ill. Adm. Code 1050), per the Endangered Species Protection Board's 2025 checklist. NatureServe: SNR, not yet ranked in Illinois. IL E&T checklist 2025
New York
Not listed Not on New York protected native plants (6 NYCRR § 193.3). NatureServe: SNR, not yet ranked in New York. 6 NYCRR § 193.3
Wisconsin
Not listed Not on Wisconsin endangered and threatened species list (Wis. Admin. Code NR 27.03). NatureServe: SNR, not yet ranked in Wisconsin. NR 27.03
Minnesota
Not listed Not on Minnesota endangered, threatened and special concern plants (Minn. R. 6134.0300). NatureServe: SNR, not yet ranked in Minnesota. Minn. R. 6134.0300
Ohio
Not listed Not on Ohio endangered and threatened plants (Ohio Adm. Code 1501:18-1-03, eff. Dec. 26, 2024). NatureServe: SNR, not yet ranked in Ohio. OAC 1501:18-1-03
North Carolina
Not listed Not on North Carolina Protected Plant Species List (02 NCAC 48F .0301). NatureServe: S5, secure in North Carolina. 02 NCAC 48F .0301
Michigan
Not listed Not on Michigan endangered and threatened plants (Mich. Admin. Code R 299.1028, eff. March 20, 2023). NatureServe: SNR, not yet ranked in Michigan. R 299.1028
Pennsylvania
Not listed Not on Pennsylvania classified native plants (17 Pa. Code Ch. 45, Subchapter B, as amended 2023). NatureServe: S5, secure in Pennsylvania. 17 Pa. Code Ch. 45
Virginia
Not listed Not on Virginia endangered and threatened plant and insect species (2VAC5-320-10). NatureServe: S5, secure in Virginia. 2VAC5-320-10
Tennessee
Not listed Not on Tennessee endangered plants (Tenn. Comp. R. & Regs. 0400-06-02-.04, Rare Plant Protection and Conservation Act). NatureServe: SNR, not yet ranked in Tennessee. TN rule 0400-06-02-.04
Massachusetts
Not listed Not on Massachusetts Endangered Species Act list (321 CMR 10.90). NatureServe: S4, apparently secure in Massachusetts. MESA list
Georgia
Not listed Not on Georgia protected plants (Ga. Comp. R. & Regs. 391-4-10-.09; a 2026 update is proposed). NatureServe: S5, secure in Georgia. Ga. R. 391-4-10-.09
Missouri
Not listed Not on Missouri Wildlife Code endangered species (3 CSR 10-4.111), plants. NatureServe: SNR, not yet ranked in Missouri. 3 CSR 10-4.111
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
New Jersey
Not listed Not on New Jersey Endangered Plant Species List (N.J.A.C. 7:5C-5.1). NatureServe: SNR, not yet ranked in New Jersey. N.J.A.C. 7:5C-5.1
Iowa
Not listed Not on Iowa endangered, threatened and special concern plants (Iowa Admin. Code r. 571-77.3). NatureServe: S4, apparently secure in Iowa. IAC 571-77.3
Kentucky
Not listed Not on Kentucky endangered and threatened plant lists (400 KAR 3:040, eff. 2026). NatureServe: SNR, not yet ranked in Kentucky. 400 KAR 3:040
Connecticut
Not listed Not on Connecticut Endangered, Threatened and Special Concern Plants (RCSA 26-306; 2015 list). NatureServe: SNR, not yet ranked in Connecticut. CT E/T/SC list
Delaware
Not listed Not on Rare and Uncommon Plants of Delaware (DNREC, 2024; informational, Delaware has no state plant-protection list). NatureServe: SNR, not yet ranked in Delaware. DE rare plants 2024
Indiana
No list Indiana has no state law listing endangered or threatened plants (the DNR keeps a rare plant list, but it isn't regulatory), so we show NatureServe's Indiana ranks instead. NatureServe: S5, secure in Indiana.
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: SNR, not yet ranked in Kansas.
Alabama
No list Alabama has no state law listing endangered or threatened plants, so we show NatureServe's Alabama ranks instead. NatureServe: SNR, not yet ranked in Alabama.
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.
South Carolina
No list South Carolina has no state law listing endangered or threatened plants, so we show NatureServe's South Carolina ranks instead. NatureServe: SNR, not yet ranked in South Carolina.
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.
West Virginia
No list West Virginia has no state law listing endangered or threatened plants (only federally listed species are protected), so we show NatureServe's West Virginia ranks instead. NatureServe: S5, secure in West Virginia.
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.
Rhode Island
Concern On Rhode Island Rare Plants 2016 (RI Natural History Survey, from the RI Wildlife Action Plan; informational, Rhode Island has no state plant-protection listing law): concern (informational). NatureServe: SNR, not yet ranked in Rhode Island. RI rare plants 2016
Rare elsewhere
Other states where NatureServe ranks it rare or missing: ME (SX), VT (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.

Please leave it where it grows

Please don't pick or dig this flower: it's on Rhode Island's rare plant list (concern). RI rare plants 2016

Can you eat it?

For peoplePoisonous to people

NC State Extension lists it as poisonous to humans (severity: low). Poisonous parts: flowers, fruits, leaves, roots, sap/juice, stems. Symptoms they list: “Can cause stomach upset, nausea, vomiting, abdominal pain, diarrhea, weakness, lethargy, and confusion if eaten in quantity. 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 butterfly milkweed in 41 states plus Washington, D.C.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

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

Illinois counties with USDA records: Adams, Bond, Boone, Calhoun, Cass, Champaign, Christian, Clark, Clay, Clinton, Coles, Cook, Crawford, Cumberland, De Witt, DeKalb, Douglas, DuPage, Edgar, Edwards, Effingham, Fayette, Ford, Gallatin, Grundy, Hamilton, Hancock, Hardin, Henderson, Iroquois, Jackson, Jasper, Jefferson, Jersey, Jo Daviess, Johnson, Kane, Kankakee, Kendall, LaSalle, Lake, Lawrence, Lee, Livingston, Logan, Macon, Macoupin, Madison, Marion, Marshall, Mason, Massac, McDonough, McHenry, McLean, Menard, Monroe, Montgomery, Morgan, Moultrie, Ogle, Peoria, Perry, Piatt, Pope, Pulaski, Randolph, Richland, Saline, Sangamon, Schuyler, Scott, Shelby, St. Clair, Stark, Stephenson, Tazewell, Union, Vermilion, Wabash, Washington, White, Whiteside, Will, Williamson, Winnebago.

New York counties with USDA records: Albany, Bronx, Chemung, Columbia, Dutchess, Erie, Herkimer, Kings, Monroe, Nassau, New York, Oneida, Onondaga, Ontario, Orange, Putnam, Queens, Rensselaer, Richmond, Rockland, Saratoga, Schenectady, Steuben, Suffolk, Sullivan, Tompkins, Warren, Washington, Westchester, Yates.

Wisconsin counties with USDA records: Adams, Bayfield, Brown, Buffalo, Burnett, Chippewa, Columbia, Crawford, Dane, Dodge, Douglas, Dunn, Eau Claire, Grant, Green, Green Lake, Iowa, Jackson, La Crosse, Lafayette, Lincoln, Manitowoc, Marinette, Marquette, Menominee, Milwaukee, Monroe, Oconto, Pierce, Polk, Portage, Racine, Richland, Rock, Sauk, Shawano, Sheboygan, St. Croix, Trempealeau, Vernon, Walworth, Washburn, Waukesha, Waupaca, Waushara, Winnebago, Wood.

Growing conditions

USDA PLANTS gives Butterfly milkweed a high shade tolerance, high drought tolerance and low moisture use. It is rated for soil pH 4.8 to 6.8 and winter lows down to -33 °F.

Shade tolerance
High
Drought tolerance
High
Moisture use
Low
Soil textures it is adapted to
coarse, medium
Soil pH range
4.8 to 6.8
Minimum temperature tolerated
-33 °F
Frost-free days needed (minimum)
135
Annual precipitation range
28 to 45 inches
Minimum root depth
16 inches
Salinity tolerance
None
Fertility requirement
Low
Growth rate
Slow
Lifespan
Moderate
Active growth period
Spring and Summer
Fruit or seed
Brown · Summer to Fall
Can be propagated by
container, seed
Commercial availability
Routinely Available

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

Names, range and relatives

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

County records: USDA PLANTS lists it in 1594 counties across 39 states; the most are in Missouri (106), Virginia (100), North Carolina (93).

Other Asclepias on Bloomipedia (16): Common milkweed, Swamp milkweed, Green antelopehorns, 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 Illinois flowers

Common milkweed (Asclepias syriaca)

Common milkweed

Asclepias syriaca

Native

🌼 Blooms in IL: June–July
Swamp milkweed (Asclepias incarnata)

Swamp milkweed

Asclepias incarnata

Native

🌼 Blooms in IL: June–August
Prairie trillium (Trillium recurvatum)

Prairie trillium

Trillium recurvatum

Native

🌼 Blooms in IL: April–May

Sources