Toxicodendron diversilobum
Common name: 
Poison Oak
toks-ee-ko-DEN-dron di-ver-si-LOW-bum
Rhus diversiloba
Native to (or naturalized in) Oregon: 
  • Broadleaf deciduous shrub, erect, 3-7 ft (1-2 m) high, or a climbing vine, sometimes up to 50 ft (15 m).  Leaves pinnately compound with 3 leaflets, each leaflet is rounded, obtuse, with a glossy upper surface, margin entire or irregularly toothed, may be highly colored (red and gold) in fall.  Flowers small, inconspicuous, yellowish-green, in loose clusters (panicles).  Fruit 5 mm diameter, white or cream colored, ribbed, in clusters, remain after leaf fall.
  • All parts of the plant are toxic, an allergic contact dermatitis.  About 70% of adults who contact poison oak or poison ivy (Toxicodendron radicans) will develop a rash in a delayed fashion from about 8 hr minimum to 2 weeks later.  The rash is due to allergic reaction to urushiol resin on leaves or stems.  Indirect contact via smoke or animals with the resin on their fur can also cause the rash to appear.  A bit of an aside: "Urushiol is the basis of oriental lacquer. The sap is conditioned by removal of most of the water by specific techniques, and the clear liquid is called oriental lacquer. It is used in the Orient for coatings to produce exquisite art objects."
  • The accepted name is Toxicodendron diversilobum, formerly Rhus diversiloba
  • Native to western parts of Washington, Oregon, and California.
  • Oregon State Univ. campus: extreme western side of campus, beyond Hinsdale Wave Lab. on Jefferson Way.
Click image to enlarge
  • young expanding leaf, early spring

    young expanding leaf, early spring

  • leaves


  • leaves, vine on tree

    leaves, vine on tree

  • fruit clusters, summer

    fruit clusters, summer

  • leafy branches, fall

    leafy branches, fall

  • branch, fall

    branch, fall

  • vines on trees, fall

    vines on trees, fall

  • leaves, fall

    leaves, fall

  • leaf and fruit, fall

    leaf and fruit, fall

  • fruit, fall

    fruit, fall