Flower profile

White snakeroot

Ageratina altissima

Native in the lower 48

White snakeroot is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 25 states, and across the U.S. it's most often seen in bloom in August–October.

37states

25of our state lists

100,651U.S. sightings*

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

On our lists for: Arkansas, Connecticut, Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, South Dakota, Tennessee, Vermont, Virginia, West Virginia, Wisconsin

Quick look

Ageratina altissima, also known as white snakeroot, richweed, or white sanicle, is a poisonous perennial herb in the family Asteraceae, native to eastern and central North America. An older binomial name for this species is Eupatorium rugosum, but the genus Eupatorium has undergone taxonomic revision by botanists, and some species once included in it have been moved to other genera.
From Wikipedia's article Ageratina altissima, CC BY-SA 4.0.

It belongs to the Asteraceae 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 37 states. ^{USDA PLANTS}
In New York, most iNaturalist sightings of it in flower come in August–October. ^iNaturalist
In Pennsylvania, most iNaturalist sightings of it in flower come in August–October. ^iNaturalist
iNaturalist has 29,434 research-grade sightings of it in New York, ranking #1 among the 109 flowers on our New York list. ^iNaturalist
iNaturalist has 11,086 research-grade sightings of it in Pennsylvania, ranking #2 among the 111 flowers on our Pennsylvania list. ^iNaturalist
iNaturalist has 8,517 research-grade sightings of it in Ohio, ranking #7 among the 109 flowers on our Ohio list. ^iNaturalist

White snakeroot gift ideas

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When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (10,085 records)

Bloom time in each of our 25 states

State	Type	Peak bloom	Sightings*
New York	Native	August–October	29,434
Pennsylvania	Native	August–October	11,086
Ohio	Native	August–October	8,517
New Jersey	Native	August–November	6,353
Illinois	Native	July–October	6,224
Wisconsin	Native	July–October	5,224
Minnesota	Native	July–September	4,710
Indiana	Native	July–October	4,155
Massachusetts	Native	August–October	2,591
Michigan	Native	August–October	2,396
Missouri	Native	August–October	2,381
Virginia	Native	July–October	1,934
Kentucky	Native	July–October	1,863
Maryland	Native	August–October	1,704
Tennessee	Native	August–October	1,291
Iowa	Native	July–September	1,228
Connecticut	Native	August–October	1,190
Vermont	Native	August–September	1,007
West Virginia	Native	August–October	957
Kansas	Native	August–October	621
Arkansas	Native	September–October	592
Delaware	Native	September–October	389
Nebraska	Native	few records	358
Rhode Island	Native	September–October	297
South Dakota	Native	few records	162

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
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}
Pennsylvania: Not listed Not on Pennsylvania classified native plants (17 Pa. Code Ch. 45, Subchapter B, as amended 2023). NatureServe: SNR, not yet ranked in Pennsylvania. ^{17 Pa. Code Ch. 45}
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}
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}
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}
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}
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.
Massachusetts: Not listed Not on Massachusetts Endangered Species Act list (321 CMR 10.90). NatureServe: SNR, not yet ranked in Massachusetts. ^{MESA list}
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}
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}
Virginia: Not listed Not on Virginia endangered and threatened plant and insect species (2VAC5-320-10). NatureServe: S5, secure in Virginia. ^2VAC5-320-10
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}
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}
Tennessee: Not listed Not on Tennessee endangered plants (Tenn. Comp. R. & Regs. 0400-06-02-.04, Rare Plant Protection and Conservation Act). NatureServe: S5, secure in Tennessee. ^{TN rule 0400-06-02-.04}
Iowa: Not listed Not on Iowa endangered, threatened and special concern plants (Iowa Admin. Code r. 571-77.3). NatureServe: SNR, not yet ranked in Iowa. ^{IAC 571-77.3}
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}
Vermont: Not listed Not on Endangered and Threatened Plants of Vermont (10 V.S.A. chap. 123; list of Feb 10, 2022). NatureServe: S5, secure in Vermont. ^{Vermont E&T list}
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.
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.
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.
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}
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}
Rhode Island: Not listed Not 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). NatureServe: SNR, not yet ranked in Rhode Island. ^{RI rare plants 2016}
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.
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 peopleCaution: partly edible, partly poisonous

NC State Extension lists it as poisonous to humans (severity: high). Poisonous parts: flowers, leaves, roots, sap/juice, seeds, stems. Symptoms they list: “The plant is highly toxic and may be fatal if eaten. Toxicity is characterized by weakness, nausea, abdominal pain, vomiting, delirium, cardiac damage, prostration and eventually, coma. Even drinking milk from cows that have eaten the plant will cause "milk…” They also note: “Toxic” ^{NC State Extension}

For petsToxic to horses

ASPCA's entry “White Snakeroot” (Ageratina altissima) lists it as toxic to horses. Signs include: All species - Weakness, stiffness, tremors, collapse; Horses - heart damage, swallowing difficulty; Goats - liver failure and… ^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 white snakeroot in 37 states plus Washington, D.C.

AKMEVTNHWAIDMTNDMNILWIMINYRIMAORNVWYSDIAINOHPANJCTCAUTCONEMOKYWVVAMDDEAZNMKSARTNNCSCDCOKLAMSALGAHITXFL

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

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

New York counties with USDA records: Albany, Bronx, Cattaraugus, Cayuga, Chautauqua, Chemung, Chenango, Columbia, Cortland, Delaware, Dutchess, Erie, Essex, Fulton, Genesee, Greene, Hamilton, Herkimer, Kings, Lewis, Livingston, Madison, Monroe, Montgomery, Nassau, New York, Oneida, Onondaga, Ontario, Orange, Oswego, Putnam, Queens, Rensselaer, Richmond, Rockland, Saratoga, Schuyler, Suffolk, Ulster, Warren, Washington, Wayne, Westchester.

Pennsylvania counties with USDA records: Adams, Allegheny, Armstrong, Beaver, Bedford, Berks, Blair, Bradford, Bucks, Butler, Cambria, Cameron, Carbon, Centre, Chester, Clarion, Clearfield, Clinton, Columbia, Crawford, Cumberland, Dauphin, Delaware, Elk, Erie, Fayette, Forest, Franklin, Fulton, Greene, Huntingdon, Indiana, Jefferson, Juniata, Lackawanna, Lancaster, Lawrence, Lebanon, Lehigh, Luzerne, Lycoming, McKean, Mercer, Mifflin, Monroe, Montgomery, Montour, Northampton, Northumberland, Perry, Philadelphia, Pike, Potter, Schuylkill, Snyder, Somerset, Sullivan, Susquehanna, Tioga, Union, Venango, Warren, Washington, Wayne, Westmoreland, Wyoming, York.

Ohio counties with USDA records: Adams, Ashland, Ashtabula, Athens, Auglaize, Belmont, Butler, Carroll, Champaign, Clark, Clermont, Clinton, Columbiana, Coshocton, Crawford, Cuyahoga, Darke, Delaware, Erie, Fairfield, Fayette, Franklin, Gallia, Geauga, Greene, Guernsey, Hamilton, Harrison, Henry, Highland, Hocking, Holmes, Huron, Jackson, Jefferson, Knox, Lake, Lawrence, Lorain, Lucas, Madison, Mahoning, Marion, Medina, Meigs, Miami, Monroe, Montgomery, Morgan, Muskingum, Ottawa, Perry, Pickaway, Pike, Portage, Richland, Ross, Sandusky, Scioto, Seneca, Stark, Summit, Trumbull, Tuscarawas, Union, Van Wert, Vinton, Warren, Washington, Wayne, Williams, Wood, Wyandot.

More New York flowers

Common yarrow

Achillea millefolium

Native

🌼 Blooms in NY: June–September

Goldenrods

Solidago

★ KY state flowerNative

🌼 Blooms: July–October

Sunflowers

Helianthus

★ KS state flowerNative

🌼 Blooms: June–October

Sources

USDA, NRCS. PLANTS Database, profile AGAL5.
iNaturalist, Ageratina altissima: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Ageratina altissima (lead quoted under CC BY-SA 4.0).
New York: New York protected native plants (6 NYCRR § 193.3).
New York: New York prohibited and regulated invasive species (6 NYCRR Part 575).
Pennsylvania: Pennsylvania classified native plants (17 Pa. Code Ch. 45, Subchapter B, as amended 2023).
Pennsylvania: Pennsylvania Noxious Weed List (3 Pa.C.S. § 1519, PA Dept. of Agriculture) (PDA's page spells garlic mustard “Allaria petiolata”; we match it as Alliaria petiolata).
Ohio: Ohio endangered and threatened plants (Ohio Adm. Code 1501:18-1-03, eff. Dec. 26, 2024).
Ohio: Ohio invasive plant species (Ohio Adm. Code 901:5-30-01).
New Jersey: New Jersey Endangered Plant Species List (N.J.A.C. 7:5C-5.1).
New Jersey: New Jersey prohibited invasive plant species (Invasive Species Management Act; propagation banned from Jan 1, 2027, sale from Jan 1, 2030).
Illinois: Illinois List of Endangered and Threatened Flora (17 Ill. Adm. Code 1050), per the Endangered Species Protection Board's 2025 checklist.
Illinois: Illinois Official List of Exotic Weeds (17 Ill. Adm. Code 1100.30, Illinois Exotic Weed Act).
Wisconsin: Wisconsin endangered and threatened species list (Wis. Admin. Code NR 27.03).
Wisconsin: Wisconsin invasive species rule (Wis. Admin. Code NR 40.04 prohibited, NR 40.05 restricted).
Minnesota: Minnesota endangered, threatened and special concern plants (Minn. R. 6134.0300).
Minnesota: Minnesota Noxious Weed List (Minn. Stat. § 18.79; Minnesota Department of Agriculture, updated January 2026).
Indiana: Indiana prohibited invasive terrestrial plants (312 IAC 18-3-25).
Massachusetts: Massachusetts Endangered Species Act list (321 CMR 10.90).
Massachusetts: Massachusetts Prohibited Plant List (MDAR) (Text from MDAR's 2023 scientific-name PDF (mass.gov blocks automated downloads); 2024-2026 additions listed on the mass.gov page: Alnus glutinosa, Pyrus calleryana, Miscanthus sinensis, Aralia elata, Rhodotypos scandens, Symplocos paniculata.).
Michigan: Michigan endangered and threatened plants (Mich. Admin. Code R 299.1028, eff. March 20, 2023).
Michigan: Michigan prohibited and restricted species (NREPA Part 413 and the 2026 Invasive Species Order), as listed by Michigan's Invasive Species Program.
Missouri: Missouri Wildlife Code endangered species (3 CSR 10-4.111), plants.
Missouri: Missouri noxious weed list (2 CSR 70-45.005).
Virginia: Virginia endangered and threatened plant and insect species (2VAC5-320-10).
Virginia: Virginia noxious weeds (2VAC5-317-20, Tier 1, 2 and 3).
Kentucky: Kentucky endangered and threatened plant lists (400 KAR 3:040, eff. 2026).
Kentucky: Kentucky noxious weeds and invasive plants on state rights-of-way (KRS 176.051; species list from the Kentucky Transportation Cabinet).
Maryland: Maryland threatened and endangered plants (COMAR 08.03.08.05, .06 and .08).
Maryland: Maryland Prohibited Invasive Plant List (COMAR 15.06.04.06; MDA, updated July 2026).
Tennessee: Tennessee endangered plants (Tenn. Comp. R. & Regs. 0400-06-02-.04, Rare Plant Protection and Conservation Act).
Tennessee: Tennessee Pest Plant List (Tenn. Comp. R. & Regs. 0080-06-24-.02).
Iowa: Iowa endangered, threatened and special concern plants (Iowa Admin. Code r. 571-77.3).
Iowa: Iowa noxious weeds (Iowa Code § 317.1A).
Connecticut: Connecticut Endangered, Threatened and Special Concern Plants (RCSA 26-306; 2015 list).
Connecticut: Connecticut prohibited invasive plants (Conn. Gen. Stat. § 22a-381d).
Vermont: Endangered and Threatened Plants of Vermont (10 V.S.A. chap. 123; list of Feb 10, 2022).
Vermont: Vermont Quarantine List, Regulated Introduced Plant Species Rule (eff. June 16, 2026).
West Virginia: West Virginia noxious weeds (W. Va. Code R. § 61-14A-5) (the rule abbreviates some names (e.g. “P. cuspidatum”); we expand them to match).
Kansas: Kansas noxious weeds (K.A.R. 4-8-44, as amended 2026).
Arkansas: Arkansas State Plant Board noxious weeds and prohibited plants (2 CAR § 50-101).
Delaware: Rare and Uncommon Plants of Delaware (DNREC, 2024; informational, Delaware has no state plant-protection list).
Delaware: Delaware Invasive Plant List (3 Del. Admin. Code § 806-3.0).
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).
Rhode Island: 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).
South Dakota: South Dakota statewide noxious weeds (ARSD 12:62:03:01.06).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Ageratina altissima (global and state ranks).
Edibility and toxicity: NC State Extension; ASPCA.
Photo: Lynn Harper via iNaturalist · CC0 · resized.