Iva annua Linnaeus. Sumpweed, Rough Marsh-elder. Phen: Aug-Nov. Hab: Fields, especially bottomlands, disturbed places; in the eastern and inland part of area probably introduced (by native Americans) from farther west. Dist: PA, ND, and CO south to FL, NM, and Mexico (the original distribution uncertain). Reported for MD (Longbottom, Naczi, & Knapp 2016).
Origin/Endemic status: Native
Syn: = C, Fl7, FNA21, GrPl, GW2, Il, K3, K4, Mi, NcTx, NE, Oh3, Pa, RAB, SE1, Tn, Tx, Va, W, WH3; = Iva ciliata Willd. – F; > Iva annua L. var. annua – K1, Jackson (1960); > Iva annua L. var. caudata (Small) R.C.Jacks. – K1, Jackson (1960); > Iva annua L. var. macrocarpa (Blake) R.C.Jacks. – K1, Jackson (1960); > Iva caudata Small – S; > Iva ciliata Willd. – S; > Iva ciliata Willd. var. ciliata – G; > Iva ciliata Willd. var. macrocarpa Blake – G