Bloomipedia
Great blue lobelia (Lobelia siphilitica)
Photo: W Rao via iNaturalist · CC BY 4.0 · resized

Flower profile

Great blue lobelia

Lobelia siphilitica

Native in the lower 48

Great blue lobelia is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 15 states, and across the U.S. it's most often seen in bloom in August–October.

37states
15of our state lists
37,926U.S. sightings*

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

On our lists for: Delaware, Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, Wisconsin

Quick look

Lobelia siphilitica, the great blue lobelia, great lobelia, or blue cardinal flower, is a plant species within the family Campanulaceae. It is an herbaceous perennial dicot native to eastern and central Canada and United States. There are two recognized varieties of Lobelia siphilitica, var. siphilitica and var. ludoviciana. Blooming from August to October, it is short-lived, lasting only for a few years.

  • It belongs to the Campanulaceae 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 Ohio, most iNaturalist sightings of it in flower come in August–September. iNaturalist
  • In Illinois, most iNaturalist sightings of it in flower come in August–October. iNaturalist
  • iNaturalist has 5,810 research-grade sightings of it in Ohio, ranking #20 among the 109 flowers on our Ohio list. iNaturalist
  • iNaturalist has 3,693 research-grade sightings of it in Illinois, ranking #33 among the 109 flowers on our Illinois list. iNaturalist
  • iNaturalist has 3,162 research-grade sightings of it in Pennsylvania, ranking #61 among the 111 flowers on our Pennsylvania list. iNaturalist

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When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (5,204 records)
Bloom time in each of our 15 states
StateTypePeak bloomSightings*
OhioNativeAugust–September5,810
IllinoisNativeAugust–October3,693
PennsylvaniaNativeAugust–October3,162
WisconsinNativeJuly–September2,689
New YorkNativeAugust–October2,688
MichiganNativeAugust–September2,678
IndianaNativeAugust–September2,397
VirginiaNativeAugust–October1,663
MinnesotaNativeAugust–September1,643
TennesseeNativeAugust–October1,436
MissouriNativeAugust–October1,356
KentuckyNativeAugust–October1,191
IowaNativeAugust–September1,069
West VirginiaNativeAugust–October673
DelawareNativeAugust–October243

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
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
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
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
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
New York
Not listed Not on New York protected native plants (6 NYCRR § 193.3). NatureServe: S5, secure in New York. 6 NYCRR § 193.3
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
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.
Virginia
Not listed Not on Virginia endangered and threatened plant and insect species (2VAC5-320-10). NatureServe: S5, secure in Virginia. 2VAC5-320-10
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
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
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
Kentucky
Not listed Not on Kentucky endangered and threatened plant lists (400 KAR 3:040, eff. 2026). NatureServe: S5, secure in Kentucky. 400 KAR 3:040
Iowa
Not listed Not on Iowa endangered, threatened and special concern plants (Iowa Admin. Code r. 571-77.3). NatureServe: S5, secure in Iowa. IAC 571-77.3
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.
Delaware
Not listed Not on Rare and Uncommon Plants of Delaware (DNREC, 2024; informational, Delaware has no state plant-protection list). NatureServe: S4, apparently secure in Delaware. DE rare plants 2024
Rare elsewhere
Other states where NatureServe ranks it rare or missing: MA (S1), ME (SX), WY (S1). (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, fruits, leaves, roots, sap/juice, seeds, stems. Symptoms they list: “Nausea, vomiting, diarrhea, salivation, exhaustion and weakness, dilation of pupils, convulsions, and coma” NC State Extension

For petsNot well documented

It isn't on the ASPCA plant list, and NC State Extension doesn't flag it for pets. For context only: ASPCA lists a related species, Lobelia cardinalis (“Cardinal Flower”), as toxic to dogs and cats. That doesn't tell us about this species, so keep pets away to be safe. 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 great blue lobelia in 37 states plus Washington, D.C.

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alabama, Arkansas, Colorado, Connecticut, Delaware, 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, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, Wisconsin, Wyoming; District of Columbia.

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

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

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, Erie, Fayette, Forest, Franklin, Fulton, Greene, Huntingdon, Indiana, Jefferson, Juniata, Lancaster, Lawrence, Lebanon, Lehigh, Luzerne, Lycoming, McKean, Mercer, Mifflin, Monroe, Montgomery, Montour, Northampton, Northumberland, Perry, Philadelphia, Pike, Schuylkill, Snyder, Somerset, Tioga, Union, Venango, Warren, Washington, Westmoreland, Wyoming, York.

More Ohio flowers

Cardinal flower (Lobelia cardinalis)

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Lobelia cardinalis

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Tall bellflower (Campanulastrum americanum)

Tall bellflower

Campanulastrum americanum

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Indian tobacco (Lobelia inflata)

Indian tobacco

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Sources