WESTERN POISON IVY

TOXICODENDRON RYDBERGII

Sumac Family, Anacardiaceae

Perennial subshrub, shrub

“Leaflets three, leave it be!” goes the rule of thumb, and for a reason. This erect plant, 1–3 (up to 6) feet tall, single-stemmed or branching, and colony-forming shrub, contains the toxic compound urushiol, which causes mild to severe skin rashes and eruptions if you are allergic to it. Clothes or pets that contact the plant can transfer the chemical to sensitive people. Note the leaves have three shiny, green leaflets; tiny, creamy flowers; and small, round fruit that birds devour and spread.

FLOWERS: May–August. Dense, elongated clusters from leaf axils; flowers 1/8 inch long (3 mm), cream to greenish-yellow. Fruit small, 3/16 inch (5 mm), round drupes in clusters.

LEAVES: Alternate. Three leaflets on the end of a 5/8–10 inch long (1.5–25 cm) stalk (petiole). Leaflet blades oval, 1–4 inches long (3–10 cm), tip pointed, surfaces usually hairless, margins unevenly toothed. Leaves turn yellow, orange, and red in the fall.

LEAVES: Alternate. Three leaflets on the end of a 5/8–10 inch long (1.5–25 cm) stalk (petiole). Leaflet blades oval, 1–4 inches long (3–10 cm), tip pointed, surfaces usually hairless, margins unevenly toothed. Leaves turn yellow, orange, and red in the fall.

ELEVATION: 5,300–9,128 feet.

RANGE: AZ, CO, NM, NV, OK, TX; Rocky Mountains, western and Great Lake states, east to Maine.

SIMILAR SPECIES: Eastern Poison Ivy, T. radicans, occurs in southern AZ and TX and eastward to the Atlantic coast, and is a climbing vine or subshrub with hairy aerial roots along the stem. Woodbine, Parthenocisus vitacea, has 5 lance-shaped leaflets. Seedling Boxelder trees, Acer negundo, have 3–5 leaflets but the leaves are opposite. Fragrant Sumac, Rhus aromatica, statewide, is a 4 foot tall and wide shrub with red fruit.

NM COUNTIES: Widespread in NM mountains from mid- to high-elevation habitats: Bernalillo, Catron, Cibola, Colfax, Dona Ana, Eddy, Grant, Hidalgo, Lincoln, Los Alamos, Luna, McKinley, Mora, Otero, Quay, Rio Arriba, San Juan, San Miguel, Sandoval, Santa Fe, Sierra, Socorro, Taos, Torrance, Union, Valencia.

Please note, this list of counties does not match the counties indicated on the range map below. We are in the process of generating new range maps and will update the range maps when able.