Smooth Sumac, Western Sumac: Rhus glabra (Synonym: Rhus glabra var. occidentalis) - Leaves pinnately compound with many leaflets. Small tree, often growing in dense thickets.
Pacific Poison-oak, Pacific Poison Oak, Poison Oak: Toxicodendron diversilobum (Synonyms: Rhus diversiloba, Toxicodendron radicans, Toxicodendron radicans ssp. diversilobum) - Leaves trilobate with rounded, obtuse, or abruptly acute tips. In the Columbia River Gorge, generally found west of The Dalles.
Pacific Poison Oak - Western Poison Ivy Hybrid: Toxicodendron diversilobum x Toxicodendron rydbergii
Poison Ivy, Western Poison-ivy: Toxicodendron rydbergii (Synonyms: Rhus radicans, Rhus radicans var. rydbergii, Rhus rydbergii, Rhus toxicodendron, Rhus toxicodendron var. vulgaris, Toxicodendron radicans var. rydbergii) - Leaves trilobate with acute or acuminate tips. In the Columbia River Gorge, found east of Tom McCall Park.