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Western Poison Oak

Toxicodendron diversilobum

Description:

This climbing vine has lobed leaves, dangling inflorescence and uses clinging roots to hold on (third image). "Western poison oak is extremely variable in growth habit and leaf appearance. It grows as a dense shrub in open sunlight, a tree with an 8–20 cm (3.1–7.9 in) trunk under conditions with ample sunlight, very wet winter/spring and dry summer, or as a climbing vine in shaded areas. Like poison-ivy, it reproduces by creeping rootstocks or by seeds.[2] The leaves are divided into three (rarely 5, 7, or 9) leaflets, 3.5 to 10 centimetres (1.4 to 3.9 in) 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. T. 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." - Wikipedia

Habitat:

Oak tree at Blue Sky Ecological Reserve

Notes:

"Western Poison oak leaves and twigs have a surface oil, urushiol, which causes an allergic reaction. Around 15%to 30% of people have no allergic response, but most, if not all, will become sensitized over time with repeated or more concentrated exposure to urushiol." - Wikipedia

1 Species ID Suggestions

HemaShah
HemaShah 12 years ago
Poison Oak
Toxicodendron diversilobum


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9 Comments

CindyBinghamKeiser
CindyBinghamKeiser 12 years ago

Thanks for sending me the ID suggestion, Emma. I didn't realize how variable this plant was in appearance. I have a spotting of this species that looks a bit different and wasn't climbing. http://www.projectnoah.org/spottings/936...

Hema  Shah
Hema Shah 12 years ago

http://www.projectnoah.org/spottings/942...
Any idea as to what this is? The flowers are tinier than shown in the picture.w

CindyBinghamKeiser
CindyBinghamKeiser 12 years ago

Thank you werdgent & Emma. I figured that's what it was but have only bothered to notice it in the fall when it's red. I didn't touch it :-)

Hema  Shah
Hema Shah 12 years ago

Poison Oak,wild strawbwerry and wild sumac have these kind of leaf arrangement.

Hema  Shah
Hema Shah 12 years ago

http://www.projectnoah.org/spottings/830...
Lots of info on poison OK in this spotting. As you scroll down the comments,there is also a video on the geographical distribution.

Hema  Shah
Hema Shah 12 years ago

Poison oak is abundant in California.

barbarossa
barbarossa 12 years ago

Some type of Toxicodendron, probably Pacific poison oak. I'm not familiar with the western species. Hope you didn't contact much of this while shooting, it causes some serious rashes.

http://plants.usda.gov/java/profile?symb...

Poway, California, USA

Spotted on Mar 21, 2012
Submitted on Mar 22, 2012

Spotted for Mission

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