• South Window

    Arches

    National Park Utah

Poison Ivy

Toxicodendron rydbergii

Toxicodendron rydbergii

Family: Anacardiaceae – Cashew Family

Dioecious shrubs; 3.9” to 11.8” (1 to 3 dm) tall or more

Leaves: alternate; compound; 3 leaflets; the terminal leaflet is 0.8” to 4.4” (2 to 11 cm) long, 0.6” to 4” (1.5 to 10 cm) wide; can have hairs

Flowers: 5 whitish to yellowish petals with dark veins, 0.08” to 0.12” (2 to 3 mm) long; 5 sepals; stamens usually 5 or 10; flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant)

Pollinators: other genera in this family are pollinated by insects (specifically bees)

Fruits: cream to yellow drupes

Blooms in Arches National Park: May, June

Habitat in Arches National Park: riparian communities

Location seen: Fiery Furnace, outside Arches National Park in Negro Bill Canyon

Other: The genus name, “Toxicodendron”, means “poison tree” and the species name, “rydbergii”, honors Per Axel Rydberg (1860-1931), a plant taxonomist and the first curator of The New York Botanical Garden Herbarium whose specialty was the flora of the Rocky Mountains and Great Plains areas.

Caution: Rubbing against this plant can produce severe dermatitis in sensitive people. All the parts, including smoke from fires containing it, should be avoided by everyone.

Did You Know?

proposed wilderness

Nearly 96% of Arches is recommended for wilderness designation. Though the recommendation has not been approved by Congress, the park is required to manage those 73,312 acres as though they were formally designated wilderness. More...