View source for Toxicodendron diversilobum

{{SPlantbox
|familia=Anacardiaceae
|genus=Toxicodendron
|species=diversilobum
|common_name=Californian poison oak, Western poison oak, Pacific Poison-oak
|name_ref=Flora - A Gardener's Encyclopedia
|habit=shrub
|habit_ref=Flora - A Gardener's Encyclopedia
|Max ht box=8
|Max ht metric=ft
|height_ref=Flora - A Gardener's Encyclopedia
|Max wd box=7
|Max wd metric=ft
|width_ref=Flora - A Gardener's Encyclopedia
|poisonous=causes allergic reaction
|poison_ref=Wikipedia
|lifespan=perennial
|exposure=sun
|sun_ref=Flora - A Gardener's Encyclopedia
|features=flowers
|flower_season=early summer, mid summer, late summer
|flower_ref=Flora - A Gardener's Encyclopedia
|flowers=white
|Temp Metric=°F
|min_zone=5
|usda_ref=Flora - A Gardener's Encyclopedia
|max_zone=10
|image=PoisonOak wb biggerLeaves.jpg
|image_width=180
|image_caption=Western Poison-oak (larger leaves; <br/>small leaves are another plant) <br/>at base of oak tree
}}
'''''Toxicodendron diversilobum''''' (syn. ''Rhus diversiloba''; '''Western Poison-oak''' or '''Pacific Poison-oak''') is a plant best known for its ability to cause allergic rashes after contact.  Western Poison-oak is found only on the [[West Coast of the United States|Pacific Coast]] of the [[United States]] and of [[Canada]]. It is extremely common in that region, where it is the predominant species of the genus; the closely related [[Atlantic Poison-oak]] (''T. pubescens'') occurs on the [[East Coast of the United States|Atlantic Coast]].  The hyphenated form "Poison-oak" is used, rather than "Poison Oak" to clearly indicate that it is not a variety of [[oak]].

Western Poison-oak is extremely variable in growth habit and leaf appearance. It grows as a dense [[shrub]] in open sunlight, or as a climbing [[vine]] in shaded areas. Like [[Poison ivy]], it reproduces by creeping [[rootstocks]] or by seeds.<ref>C.Michael Hogan (2008) [http://globaltwitcher.auderis.se/artspec_information.asp?thingid=82914 "Western poison-oak: Toxicodendron diversilobum"], GlobalTwitcher, ed. Nicklas Strömberg</ref> The leaves are divided into three [[leaflets]], 3.5 to 10 centimeters long, with scalloped, toothed, or lobed edges- generally resembling the leaves of a true oak, though the Western Poison-oak leaves will tend to be more glossy. Leaves are typically bronze when first unfolding, bright green in the spring, yellow-green to reddish in the summer, and bright red or pink in the fall. White flowers form in the spring and, if fertilized, develop into greenish- white or tan berries. ''Toxicodendron diversilobum'' is winter [[deciduous]], so that after cold weather sets in the stems are leafless and bear only the occasional cluster of berries.  Without leaves, poison oak stems may sometimes be identified by occasional black marks where its milky sap may have oozed and dried.

==Cultivation==


===Propagation===


===Pests and diseases===


==Varieties==


==Gallery==

<gallery perrow=5>
Image:PoisonOakGreenPhase.jpg|Green phase
Image:PoisonOakRedPhase.jpg|Red phase
Image:Toxicodendron_diversilobum_berries.jpg|Berries
Image:Pacific-Poison-Oak.jpg|Pacific Poison-oak
Image:PoisonOak wb smallerLeaves.jpg|Ground variation
Image:ClimbingPoisonOak.jpg|Climbing variation
</gallery>

==References==
<references/>
<!--- xxxxx  *Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881925381  -->
<!--- xxxxx  *American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432  -->
<!--- xxxxx  *Sunset National Garden Book. Sunset Books, Inc., 1997. ISBN 0376038608  -->

==External links==
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