Woody vine or shrub 1.2 m long (vine) or 45 cm tall (shrub). Leaves: alternate, hairy-stalked (2 - 16 cm long), with three leaflets (trifoliate). Flowers: either male or female, growing on separate plants (dioecious), borne on a loosely branched inflorescence (panicle), usually with more than 25 flowers per inflorescence. The five petals are cream-colored to yellowish green, 2 - 5 mm long, and larger in male flowers. Flowers may develop even in very young plants. Fruit: fleshy with a center seed (drupe), borne on stalked clusters often hanging downward, each drupe to 4.5 mm across, hairless or with few scattered hairs. Seeds are round, white to cream, sometimes with gray stripes. Leaflets: stalked (middle leaflet stalk longest), reddish purple when young, becoming glossy green, 3 - 15 cm long, egg-shaped to elliptic with a pointed tip, coarsely toothed to few-lobed, thin. The lower surface may have appressed hairs, hairs along the midveins, or may be hairless. Form: climbing or trailing, rarely suberect, often with aerial roots, spreading by rhizomes to form colonies.
Similar species: The typical variety of this species has hairless fruit. The hybrid between Toxicodendron radicans ssp. negundo and Toxicodendron rydbergii is intermediate in characteristics, and can be distinguished by its wider and few-toothed leaflets and its hairless to lightly hairy leafstalks.
Flowering: late May to late June
Habitat and ecology: Very common in many habitats including fields, woodlands, wooded floodplains, bluffs, dune slopes facing Lake Michigan, disturbed areas, and sandy black oak savannas. This subspecies is usually found west of the Appalachian Divide.
Occurence in the Chicago region: native
Notes: Avoid touching this plant, as it contains a toxic compound called urushiol. Do not burn it, as the toxin is released into the air and can be inhaled. After contact with urushiol, a person sesitive to the toxin becomes itchy, and within 24 - 48 hours the skin blisters and reddens. If tools or clothing have been contaminated, they should be washed with hot water and soap.
Etymology: Toxicodendron means "poison tree." Radicans means "having rooting stems." Negundo comes from a Sanskrit name for Vitex negundo, referring to the similarity of the leaves.