Vascular Plants of North Carolina
Account for Giant Ironweed - Vernonia gigantea   (Walter) Trelease
Members of Asteraceae:
Members of Vernonia with account distribution info or public map:
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Section 6 » Order Asterales » Family Asteraceae
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Author(Walter) Trelease
DistributionThis is a species that is easily overlooked among V. noveboracensis, a common NC species. The county range map below is almost certainly incomplete, but some county "records" far east of the Mountains might well be open to question. On the other hand, given the habitat availability, there seems no reason -- if the Fall Line records are correct -- for it not also to be present across most of the Piedmont. The BONAP map also includes Alleghany and Watauga counties, reasonable given the overall range (included on the map) and Bladen County (likely out of range and not included on the map below). Nonetheless, this species is genuinely rare east of the TN-NC state line, and also rather scarce in VA but yet widespread in WV. Contrarily, V. noveboracensis is genuinely scarce in TN and the western half of WV, yet found in nearly every county in VA and NC! The BONAP maps for these two species show this dichotomy very well.

NY to NE, south to SC, northern FL, and TX.
AbundanceProbably rare in the Mountains, and very rare in the Piedmont, Sandhills, and western Coastal Plain. A small population (15 plants) was discovered in the Piedmont of Moore County in September 2020; plants ranged from 6-9 feet tall. Another small population was discovered and photographed in Johnston County by K. Taylor (photos on Facebook), also in September 2020. Becky Dill vouchered a population in Anson County in 2022; and a population was photographed in Wilson County in 2023 by Mark Basinger. This should be a Significantly Rare species or at a minimum a Watch List species, but NCNHP does not have it on either list (and does not yet have a State Rank for it). The website editors have given it a W7 status (Rare but poorly known). The S2? State Rank suggested by the editors is a rough guess, based on the fact that it should not be overly rare in the mountains.
HabitatMoist to wet soil of marshes, streamsides, wet meadows, low spots in pastures.
PhenologyFlowering and fruiting August-October.
IdentificationGiant Ironweed is indeed tall -- up to 7 or more feet. Leaves are numerous and shaped like those of New York Ironweed (V. noveboracensis), which is far more commonly encountered in NC. It is best told from the latter by fewer-flowered heads (9-30 vs. 30-50) and acute to blunt tips of involucral bracts (vs. acuminate). This species also is downy on the underside of the leaves, whereas New York Ironweed is smooth. Also, the involucre is shorter (less than 7 mm) and florets fewer (less than 30) than in New York Ironweed. This species is presumably overlooked in the mountains among the quite common New York Ironweed. Both species are quite majestic in bloom.
Taxonomic CommentsTreated as V. altissima in RAB (1968) and many other references.

Other Common Name(s)Tall Ironweed. Note that many references use Tall Ironweed for the shorter and much more slender V. angustifolia. As a result, the website editors wish to avoid confusion with common names, and use Slender Ironweed for this latter species.
State Rank[S2?]
Global RankG5
State Status[W7]
US Status
USACE-agcpFAC link
USACE-empFAC link
County Map - click on a county to view source of record.
Photo Gallery
Mark BasingerWilson County, 26 Sept 2023 WilsonPhoto_natural
Mark BasingerWilson County, 26 Sept 2023 WilsonPhoto_natural
B.A. SorrieSame data, Atlantic Road. MoorePhoto_natural
B.A. SorriePiedmont, Atlantic Road E of Lackey Siding Road, 6 Sept 2020. MoorePhoto_natural
Will StuartRichmond County, Sept 2021, Hough Road, dense population. RichmondPhoto_natural
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