Toxicodendron rydbergii (Small ex Rydberg) Greene. Western Poison Ivy. Phen: May-Jul. Hab: Acid pine-oak forests and woodlands at moderate elevations. Dist: NS west to BC, south to New England, NY, n. OH, n. IL, IA, w. KS, w. TX, AZ, Mexico (CHH, SON), and OR; disjunct in the Appalachians in PA, WV, and VA. Reported for NC by Gillis (1971), but the location (Cumberland Co., in the fall-line Sandhills), does not seem plausible {investigate further with specimen}.

Origin/Endemic status: Native

Synonymy: = C, GrPl, Il, K1, K3, K4, Mex, Mi, NE, NY, Ok, Pa, Va, Gillis (1971), Greene (1905); = n/a – RAB, S; = Rhus radicans L. var. rydbergii (Small) Rehder – F, G, WV; = Toxicodendron radicans (L.) Kuntze var. rydbergii (Small ex Rydb.) Erskine – NeUS

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Wetland Indicator Status:

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

Heliophily: 7