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Toxicodendron diversilobum
WESTERN POISON OAK

Higher Taxonomy
Family: AnacardiaceaeView DescriptionDichotomous Key

Common Name: SUMAC or CASHEW FAMILY
Habit: Shrub, tree; generally dioecious or flowers bisexual and unisexual; resin clear, often weathering black, generally aromatic, latex milky or 0. Leaf: simple to ternate- or odd-pinnate-compound, alternate, deciduous or evergreen; stipules 0. Inflorescence: raceme or panicle; flowers generally many. Flower: generally unisexual, radial; sepals generally 5, base generally +- fused; petals 5, generally > sepals, free; (perianth parts 1--7 in Pistacia); stamens 4--7 or 10, vestigial in pistillate flowers; ovary superior, vestigial or 0 in staminate flowers, subtended by +- lobed, disk-like nectary, chamber generally 1, ovule generally 1, styles 1--3. Fruit: drupe-like, generally +- flat, sticky or not, hairs short or 0; pulp +- resinous, aromatic or not.
Genera In Family: 70+ genera, +- 850 species: tropics, warm temperate; some ornamental (Rhus, Schinus), cultivated for fruit (Anacardium, cashew; Mangifera, mango; Pistacia, pistachio). Toxicity: TOXIC: many genera produce contact dermatitis.
eFlora Treatment Author: John M. Miller & Dieter H. Wilken, except as noted
Scientific Editor: Bruce G. Baldwin, Thomas J. Rosatti.
Genus: ToxicodendronView Description 

Common Name: POISON OAK, POISON IVY
Habit: Shrub, vine-like or not; generally dioecious. Leaf: +- resinous; leaflets 3--9, thin to +- leathery, entire, toothed, or lobed. Inflorescence: raceme or panicle, axillary, +- open; flowers pedicelled. Flower: stamens 5, vestigial in pistillate flowers; styles +- fused, stigmas 3. Fruit: generally spheric, papery or leathery in age, cream to brown; pulp resinous.
Species In Genus: 15 species: America, eastern Asia. Etymology: (Latin: poisonous tree) Toxicity: TOXIC: resin on leaves, stems, fruits causes severe contact dermatitis; one of the most hazardous plants in California.

Toxicodendron diversilobum (Torr. & A. Gray) Greene
NATIVE
Habit: Shrub, 0.5--4 m, or vine-like, < 25 m. Stem: twigs gray- to red-brown, tapered, hairs 0 to sparse. Leaf: petiole 1--10 cm; leaflets 3(5), +- round to oblong, entire, wavy, or +- lobed, thin to +- leathery, bright red in fall, adaxially glabrous, shiny, abaxially sparse-short-hairy, base truncate to rounded, tip obtuse to rounded; terminal leaflet 1--13 cm, 1--8 cm wide, lateral 1--7 cm, 1--6 cm wide. Inflorescence: branches loose, generally arched, slender; pedicels 2--8 mm; bractlets < 1 mm. Flower: sepals green; petals > sepals, generally ovate, yellow- to white-green. Fruit: 1.5--6 mm diam, spheric to +- compressed, glabrous to fine-bristly, creamy white, in age leathery; pulp white, black-striate. Chromosomes: 2n=30.
Ecology: Canyons, slopes, chaparral, coastal scrub, oak woodland; Elevation: < 1650 m. Bioregional Distribution: CA-FP, sw edge DMoj; Distribution Outside California: to British Columbia, western Nevada, northern Baja California. Flowering Time: Apr--Jun
Synonyms: Rhus diversiloba Torr. & A. Gray
Unabridged Note: A related sp., Toxicodendron rydbergii (Small ex Rydb.) Greene, occurs in southeastern Oregon, Nevada, Utah, western Arizona.
eFlora Treatment Author: John M. Miller & Dieter H. Wilken
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Citation for this treatment: John M. Miller & Dieter H. Wilken 2016. Toxicodendron diversilobum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=46791, accessed on July 29, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on July 29, 2016.


Toxicodendron diversilobum
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© 2011 Julie Kierstead Nelson
Toxicodendron diversilobum
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© 2001 Tony Morosco
Toxicodendron diversilobum
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© 2009 Barry Rice
Toxicodendron diversilobum
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© 2014 California Academy of Sciences
Toxicodendron diversilobum
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© 2011 Julie Kierstead Nelson
Toxicodendron diversilobum
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© 2014 Keir Morse

More photos of Toxicodendron diversilobum in CalPhotos


Geographic subdivisions for Toxicodendron diversilobum:
CA-FP, sw edge DMoj;
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.