PlantFiles: Rydberg's Poison Ivy, Western Poison Ivy
Toxicodendron rydbergii

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 good distance away from woodland edge, but it depends on how thick the grasses are - it won't surivive in open areas without some shrub or tree to thin out the grasses with their shade.

It doesn't care whenever the site it grows on are dry or moist - I have seen it grow on dry sandy soil and on rich floodplain soil.

A better common name is shrub poison ivy as it is also found in the northern part of East United States so Western Poison Ivy is not really a good name.

By Plant Profiles, the range of this species includes most of Western US, all of South Canada, and the northern part of East US down to Virginia.