Close up of poison oak leaves.  Copyright © 2005 by Lawrence M. Kelly



Domain- Eukarya

The Pacific Poison Oak plant is classified in the domain Eukarya because it has a true membrane bound nucleus. Other members: Elephants, Dogs, Coastal Redwood, Brown Algae

Kingdom- Plantae 

There are two main reasons Poison Oak is classified under the kingdom Plantae.  The first reason is they have cell walls made of cellulose a unique characteristic only found in this kingdom.  The second reason is the presence of chloroplasts which allow for photosynthesis to occur, which is another characteristic found only in this kingdom.  Other Members: Grass, Daisies, Australian Pine Tree 

This a phylogenetic tree showing the evolution of land plants through the three domains and the seven super groups.  Help with creating this was found at

Phylum - Angiosperm

Pacific Poison Oak is classified under the phylum angiosperm because it is a flowering plant who's ovules and seeds are protected by an ovary wall in a carpel which will eventually become the fruit.  Other Members: Rose Bush, Orange Tree, Marigolds

Class- Dicotyledons

This class known as Magnoliopsida or Dicotyledons means that the Poison Oak has seeds with two embryonic leaves known as cotyledones. Other Members: Carrots, Dogwood, Milkweed


This order is mainly composed of woody plants much like the Poison Oak.  Another feature that this order sees is compound leaves. Other Members: Citrus, Maples, Horse-chestnuts, Mahogany

Family - Anacardiaceae – Sumac or Cashew family

This family is primarily trees and shrubs that possess resin canals with a clear to milky fluid known as exudate.  In the case of the Poison Oak it is known as urushiol which causes the skin irritation associated with the plant.  Other Members: Mango Tree, Lacquer Tree, Cashews, Pistachio

Genus- Toxicodendron Mill. 

This genus is comprised of woody trees, shrubs, and vines such as the Poison Oak that produce the skin irritating oil known as urushiol. Other Members: Poison Ivy and Poison Sumac

This phylogenetic tree shows the order sapindales and its path to the toxicodendron genera.    Help with creating this was found at

Species- Toxicodendron diversilobum (Torr. & A. Gray) Greene 

Pacific poison oak Toxicodendron meaning ”toxic tree"  in Greek and diversilobum meaning "diversely lobed".  


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