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This is a native species.

Toxicodendron rydbergii
Toxicodendron rydbergii (Poison Ivy)
Anacardiaceae (Sumac Family)

Semi-desert, foothills, montane. Streamsides, seeps. Spring.
Lower Dolores River Canyon, May 17, 2004.

This is one plant we all should get to know in all of its varying phases.  Leaflets usually emerge red and are three in a cluster; flowers are tiny and white/yellow; berries are clustered and off-white; stems are dull brown with conspicuous sloped scars where previous leaves were attached.  Plants shown here are typical: clustered, upright, and about two feet tall, but they do grow to about six feet tall in the Four Corners area.  The eastern Poison Ivy, Toxicodendron radicans, commonly has a main stem of several inches in diameter and climbs high into trees as a hairy vine.

In the dry Southwest, Poison Ivy is nowhere near as common as it is in the East, but it is just as toxic.  Look out for it even in very dry surroundings, for even though it may not be found for miles along a dry trail, when you take your lunch break at the base of cliffs, near seeps and springs, or near an alcove hanging garden, you are apt to find it.  The juices of all parts of the plant are active any time of the year and cause severe itching in most people.  As is true of many allergic reactions, each person's reaction to Poison Ivy can change during their lifetime.

The genus, Toxicodendron, was named by Philip Miller and the species, first named Rhus rydbergii by Small in 1900, was renamed Toxicodendron rydbergii by Edward Greene in 1905.  T. rydbergii was first collected in Utah by L. F. Ward in 1875.   "Toxicodendron" is Greek for  "poison tree".  "Rydbergii" is for Per Axel Rydberg, one of the most eminent of 19th and early 20th century botanists. (Click for more biographical information about Rydberg.)

Toxicodendron rydbergii
Toxicodendron rydbergii (Poison Ivy)
Anacardiaceae (Sumac Family)

Semi-desert, foothills, montane. Streamsides, seeps. Spring.
Haviland Lake Trail, June 27, 2005.

Flowers are in two-to-three inch sprays and are followed by off-white berries that are eaten by a number of birds.

Toxicodendron rydbergii (Poison Ivy)
Toxicodendron rydbergii (Poison Ivy)
Anacardiaceae (Sumac Family)

Semi-desert, foothills, montane. Streamsides, seeps. Spring.
Lower Dolores River Canyon, May 17, 2004.

When new, leaves are maroon/red and change to green as chlorophyll develops. Click to see how similar the leaves of Poison Ivy are to those of Box Elder.

Toxicodendron rydbergii (Poison Ivy)
Toxicodendron rydbergii (Poison Ivy)
Anacardiaceae (Sumac Family)

Semi-desert, foothills, montane. Streamsides, seeps. Spring.
Piedra River, August 20, 2005.

In the fall, chlorophyll fades and lovely fall colors attract many unwary leaf collectors.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Toxicodendron rydbergii