Heracleum maximum W. Bartram. Masterwort, Cow-parsnip, American Hogweed. Phen: May-Jul; Jul-Aug. Hab: Northern hardwood forests, roadbanks, meadows, forest openings, grassy balds, rich floodplain forests. Dist: NL (Labrador) west to AK, south to DE, PA, OH, IN, IL, MO, KS, NM, AZ, CA, and in the Appalachians south to w. NC, e. TN, and n. GA; also in e. Siberia.

Origin/Endemic status: Native

Taxonomy Comments: The synonymy reflects two questions, one nomenclatural, the other taxonomic. North American plants are very similar to European ones, leading some workers to treat our plants as a subspecies or variety of the European. If recognized as specifically distinct from Eurasian H. sphondylium, the nomenclatural question is whether to accept Bartram's (older) name as validly published.

Synonymy: = F, FNA, GW2, Il, K1, K3, K4, Mi, NE, NY, Tn, Va, WV; = Heracleum lanatum Michx. – C, G, MC, Pa, RAB, Tat, W; = Heracleum sphondylium L. ssp. montanum (Schleich. ex Gaudin) Briq. – GrPl, Mo2; = Heracleum sphondylium L. var. lanatum (Michx.) Dorn

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FAC
• Eastern Mountains and Piedmont: FAC
• Great Plains: FAC
• Midwest: FACW
• Northcentral & Northeast: FACW

Heliophily: 5