Asclepias quadrifolia Jacquin. Fourleaf Milkweed. Phen: May-Jun; Aug-Sep. Hab: Moist to dryish forests and forest margins, most common on mafic and calcareous substrates. Dist: NH and NY west to IN, south to NC, n. GA, n. AL, and c. TN; also from w. IL west to MO, south to AR and OK.
Origin/Endemic status: Native
Syn: = Ar, C, F, G, GrPl, Il, K1, K3, K4, Mo2, NE, NY, Pa, RAB, S, Tn, Va, W, Woodson (1954)