Ambrosia trifida Linnaeus var. texana Scheele. Texas Giant Ragweed. Phen: Jul-Nov. Hab: Floodplains, moist pastures; disturbed ground. Dist: S. IL and MO south to MS, s. TX, and Mexico (CHH, COA, HGO, QRO, SON, TAM, VER).

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, NcTx, Tx; = Ambrosia aptera DC. – S; < Ambrosia trifida L. – Ar, FNA21, K3, K4, Mex, Mo2, Ok, SE1

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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