Rydberg's Poison Ivy, Western Poison Ivy

Toxicodendron rydbergii

Family: Anacardiaceae (an-a-kard-ee-AY-see-ee) (Info)
Genus: Toxicodendron (toks-ee-ko-DEN-dron) (Info)
Species: rydbergii (ryd-BERG-ee-eye) (Info)
Synonym:Rhus radicans var. rydbergii
Synonym:Rhus radican var. vulgaris
Synonym:Rhus toxicodendron var. vulgaris
Synonym:Toxicodendron desertorum
Synonym:Toxicodendron radicans var. rydbergii


Vines and Climbers

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Unknown - Tell us

Where to Grow:

Unknown - Tell us


6-8 ft. (1.8-2.4 m)


Unknown - Tell us


USDA Zone 3a: to -39.9 C (-40 F)

USDA Zone 3b: to -37.2 C (-35 F)

USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

Sun Exposure:

Sun to Partial Shade


All parts of plant are poisonous if ingested

Handling plant may cause skin irritation or allergic reaction

Bloom Color:

White/Near White

Bloom Time:

Late Spring/Early Summer

Mid Summer

Late Summer/Early Fall




Good Fall Color

Other details:

May be a noxious weed or invasive

Soil pH requirements:

Unknown - Tell us

Patent Information:


Propagation Methods:

Unknown - Tell us

Seed Collecting:

Unknown - Tell us


This plant has been said to grow in the following regions:

Boulder, Colorado

Mackinaw, Illinois

Minneapolis, Minnesota

Hulbert, Oklahoma

Conway, South Carolina

Baytown, Texas

Celeste, Texas

show all

Gardeners' Notes:


On Jun 7, 2010, ElecCham from Lafayette, CO wrote:

I've lived back and forth between Colorado and in Illinois for pretty much my whole life. From the Midwest, I was plenty familiar with poison ivy, and didn't seem to be affected by it. At camp one year, I'd tripped and fallen - right into a bed of the stuff. I showered off and washed my clothes, but apparently for others' benefit more than my own.

The previous house I lived in here in Colorado was very near Boulder Creek, right on the side of a hill. I was doing some gardening work... and then *later* learned about Western poison ivy. Apparently I am only immune to the Eastern variety...

Forget what you knew about how it looks, other than that it has three leaves; if the ones I had were any good example, the leaves are fairly light green, smooth, thin, an... read more


On Feb 9, 2009, Malus2006 from Coon Rapids, MN (Zone 4a) wrote:

This species of poison ivy is strongly shrub form - it never vines at all. In Minnesota where I live, I have never had seen vining form of poison ivy anywhere in the state. In shrub form, it is mainly a single wood stem, rarely branching. Most of the poison ivy I have seen tend to be less than one foot, making them look almost like they are "vining" along the ground when in reality they are rhizome through the ground, coming up in short wood stems. In certain favorable conditons, so far I have seen mainly floodplain habitation, they get tall - one was almost my height at five feet. In late fall to winter, their white berries atop their wood stems can look odd, especially in grassy areas. This species strongly favors woodland edges, and rarely go far deeper in the woodland. It can extend a... read more