Ambrosia trifida Linnaeus var. trifida . Giant Ragweed. Phen: Jul-Nov. Hab: Floodplains, moist pastures, disturbed ground. Dist: NS and BC south to n. peninsular FL, Panhandle FL, TX, and CA. Report from s. FL (Kartesz 2022) is false, based on misidentified specimen.

Origin/Endemic status: Native

Taxonomy Comments: The distinction between var. trifida and var. texana (or at the specific rank A. trifida and A. aptera) warrants additional study.

Synonymy: = C, F, G, GrPl, Il, NE; = Ambrosia trifida L. – S; < Ambrosia trifida L. – Fl7, FNA21, K3, K4, Mi, Mo2, NY, Oh3, Ok, Pa, RAB, SE1, Tat, Tn, Va, WH3, McMillan & Prevost (2022)

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FAC (taxonomic split from wetland indicator species)
• Eastern Mountains and Piedmont: FAC (taxonomic split from wetland indicator species)
• Great Plains: FAC (taxonomic split from wetland indicator species)
• Midwest: FAC (taxonomic split from wetland indicator species)
• Northcentral & Northeast: FAC (taxonomic split from wetland indicator species)

Heliophily: 6