Achillea gracilis Rafinesque. Eastern Yarrow, Eastern Thousandleaf. Phen: Apr-Nov. Hab: Grassy balds, meadows, pastures, roadsides, disturbed areas. Dist: Widespread in e. North America.

Origin/Endemic status: Native

Taxonomy Comments: The Achillea millefolium aggregate is a taxonomically very complex entity, with races of different ploidies, and both introduced and native genotypes in e. North America. Ramsey, Robertson & Husband (2008) recommended treating native North American races as A. borealis; most eastern North American populations represent native North American races, most closely allied to e. Asian taxa, with only a few collections of European races from near old port cities (Ramsey, pers. comm.; Ramsey 2011; Levin 2011). Later work suggests that A. borealis should be narrowly applied to a western North American entity, and that the oldest name available for native eastern North American Achillea is A. gracilis, a course followed here.

Synonymy ⓘ: = Achillea lanulosa Nutt. – Arriagada & Miller (1997); = Achillea millefolium L. ssp. lanulosa (Nutt.) Piper – G, GrPl, W; = Achillea millefolium L. var. occidentalis DC. – K1; < Achillea borealis Bong. – Ramsey, Robertson, & Husband (2008); >< Achillea borealis Bong. – F; >< Achillea lanulosa Nutt. – F; < Achillea millefolium L. – Ar, Fl7, FNA19, K4, Mi, NcTx, NY, Oh3, Ok, Pa, RAB, SE1, Tat, Tn, Va, WH3; < Achillea millefolium L. ssp. lanulosa (Nutt.) Piper – NE; > Achillea millefolium L. ssp. lanulosa (Nutt.) Piper – C; > Achillea millefolium L. var. lanulosa (Nutt.) Piper – Il; >< Achillea millefolium L. var. millefolium – Il; > Achillea millefolium L. var. nigrescens (Nutt.) Piper – C

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Wetland Indicator Status:

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

Heliophily ⓘ: 8