„Toxicodendron diversilobum“ – Versionsunterschied

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{{merge from|poison oak}}
{{Taxobox
{{Italic title}}{{Taxobox
|name= ''Toxicodendron diversilobum''<br/>Pacific poison oak
| name= ''Toxicodendron diversilobum''<br/>Pacific poison oak
|image = PoisonOak wb biggerLeaves.jpg
| image = PoisonOak wb biggerLeaves.jpg
|image_caption = Pacific poison oak (larger leaves) at base of an oak tree.
| image_caption = Pacific poison oak (larger leaves) at base of an oak tree.
|regnum = [[Plant]]ae
| regnum = [[Plant]]ae
|unranked_divisio = [[Angiosperms]]
| unranked_divisio = [[Angiosperms]]
|unranked_classis = [[Eudicots]]
| unranked_classis = [[Eudicots]]
|unranked_ordo = [[Rosids]]
| unranked_ordo = [[Rosids]]
|ordo = [[Sapindales]]
|familia = [[Anacardiaceae]]
| ordo = [[Sapindales]]
| familia = [[Anacardiaceae]]
|genus = ''[[Toxicodendron]]''
| genus = ''[[Toxicodendron]]''
|species = '''''T. diversilobum'''''
|binomial = ''Toxicodendron diversilobum''
| species = '''''T. diversilobum'''''
⚫
| binomial = ''Toxicodendron diversilobum''
|binomial_authority = ([[John Torrey|Torr.]] & [[Asa Gray|A.Gray]]) [[Edward Lee Greene|Greene]]
| binomial_authority = ([[John Torrey|Torr.]] & [[Asa Gray|A.Gray]]) [[Edward Lee Greene|Greene]]
⚫
|}}
| synonyms = ''Rhus diversiloba'' <small>Torr. & A.Gray</small>
⚫
}}
'''''Toxicodendron diversilobum''''', commonly named '''Pacific poison oak''' or '''western poison oak''' (syn. ''Rhus diversiloba''), is in the [[Anacardiaceae]] family (the sumac family).
'''''Toxicodendron diversilobum''''', commonly named '''Pacific poison oak''' or '''western poison oak''' (syn. ''Rhus diversiloba''), is in the [[Anacardiaceae]] family (the sumac family).


The woody vine or shrub is widely distributed in western North America, inhabiting conifer and mixed broadleaf forests, woodlands, grasslands, and [[chaparral]] biomes.<ref name="Hogan">C. Michael Hogan (2008); [http://globaltwitcher.auderis.se/artspec_information.asp?thingid=82914 "Western poison-oak: Toxicodendron diversilobum"], GlobalTwitcher, ed. Nicklas Strömberg</ref> It is known for causing itching and allergic rashes in many humans, after contact by touch or smoke inhalation.
The woody vine or shrub is widely distributed in western North America, inhabiting conifer and mixed broadleaf forests, woodlands, grasslands, and [[chaparral]] biomes.<ref name="Hogan">C. Michael Hogan (2008); [http://globaltwitcher.auderis.se/artspec_information.asp?thingid=82914 "Western poison-oak: ''Toxicodendron diversilobum''"], GlobalTwitcher, ed. Nicklas Strömberg</ref> It is known for causing itching and allergic rashes in many humans, after contact by touch or smoke inhalation.


==Distribution==
==Distribution==
The Pacific poison-oak ''[[Toxicodendron]]'' species is found in [[California]], the [[Baja California peninsula]], [[Nevada]], [[Oregon]], [[Washington (state)|Washington]], and [[British Columbia]].<ref>{{PLANTS |symbol=TODI |taxon=Toxicodendron diversilobum |accessdate=2013-09-20}}</ref> The related [[Toxicodendron pubescens|Eastern poison oak (''Toxicodendron pubescens'')]] is native to the [[Southeastern United States]]. Pacific poison-oak and [[Toxicodendron rydbergii|Western poison-ivy (Toxicodendron rydbergii)]] hybridize in the [[Columbia River Gorge]] area.<ref name="usfs">[http://www.fs.fed.us/database/feis/plants/vine/toxdiv/all.html U.S. Forest Service: ''Toxicodendron diversilobum'']</ref>
The Pacific poison-oak ''[[Toxicodendron]]'' species is found in [[California]], the [[Baja California peninsula]], [[Nevada]], [[Oregon]], [[Washington (state)|Washington]], and [[British Columbia]].<ref>{{PLANTS |symbol=TODI |taxon=Toxicodendron diversilobum |accessdate=2013-09-20}}</ref> The related [[Toxicodendron pubescens|eastern poison oak (''Toxicodendron pubescens'')]] is native to the [[Southeastern United States]]. Pacific poison-oak and [[Toxicodendron rydbergii|western poison-ivy (''Toxicodendron rydbergii'')]] hybridize in the [[Columbia River Gorge]] area.<ref name="usfs">[http://www.fs.fed.us/database/feis/plants/vine/toxdiv/all.html U.S. Forest Service: ''Toxicodendron diversilobum'']</ref>


''Toxicodendron diversilobum'' is common in various [[habitat]]s, from mesic [[riparian zone]]s to xeric [[chaparral]].<ref name="jepson">[http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=46791 Jepson]</ref> It thrives in shady and dappled light through full and direct sunlight conditions, at elevations below {{convert|5000|ft|m}}.<ref name="usfs"/> The vining form can climb up large shrub and tree trunks into their canopies. Sometimes it kills the support plant by smothering or breaking it.<ref name="usfs"/>
''Toxicodendron diversilobum'' is common in various [[habitat]]s, from mesic [[riparian zone]]s to xeric [[chaparral]].<ref name="jepson">[http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=46791 Jepson]</ref> It thrives in shady and dappled light through full and direct sunlight conditions, at elevations below {{convert|5000|ft|m}}.<ref name="usfs"/> The vining form can climb up large shrub and tree trunks into their canopies. Sometimes it kills the support plant by smothering or breaking it.<ref name="usfs"/>


The plant often occurs in [[California chaparral and woodlands|chaparral and woodlands]], [[coastal sage scrub]], [[grassland]]s, and [[California oak woodland|oak woodland]]s; and [[Douglas-fir|Douglas-fir (''Pseudotsuga menzesii'')]], Hemlock—Sitka spruce, [[Sequoia sempervirens|Coast redwood (''Sequoia sempervirens'')]], [[Pinus ponderosa|Yellow Pine (''Pinus ponderosa'')]], and [[:California mixed evergreen forest|mixed evergreen forest]]s.<ref>[http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Toxicodendron+diversilobum Calflora]</ref>
The plant often occurs in [[California chaparral and woodlands|chaparral and woodlands]], [[coastal sage scrub]], [[grassland]]s, and [[California oak woodland|oak woodlands]]; and [[Douglas-fir|Douglas-fir (''Pseudotsuga menzesii'')]], hemlock–Sitka spruce, [[Sequoia sempervirens|coast redwood (''Sequoia sempervirens'')]], [[Pinus ponderosa|yellow pine (''Pinus ponderosa'')]], and [[California mixed evergreen forest|mixed evergreen forests]].<ref>[http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Toxicodendron+diversilobum Calflora]</ref>


==Description==
==Description==
''Toxicodendron diversilobum'', Pacific or western poison oak, is extremely variable in growth habit and leaf appearance. It grows as a dense {{convert|0.5|-|4|m|ft}} tall [[shrub]] in open sunlight, a treelike [[vine]] {{convert|10|-|30|ft}} and may be more than more than {{convert|100|ft|m}} long with an {{convert|8|-|20|cm|in|abbr=on}} trunk, as dense thickets in shaded areas, or any form in between <ref name="usfs"/><ref>[http://eol.org/pages/582277/hierarchy_entries/46207742/overview Integrated Taxonomic Information System (ITIS): ''Toxicodendron diversilobum'' (Western Poison-oak) - Overview]</ref> It reproduces by spreading [[rhizome]]s and by seeds.<ref name=Hogan>Hogan, 2008</ref>
''Toxicodendron diversilobum'', Pacific or western poison oak, is extremely variable in growth habit and leaf appearance. It grows as a dense {{convert|0.5|-|4|m|ft}} tall [[shrub]] in open sunlight, a treelike [[vine]] {{convert|10|-|30|ft}} and may be more than more than {{convert|100|ft|m}} long with an {{convert|8|-|20|cm|in|abbr=on}} trunk, as dense thickets in shaded areas, or any form in between <ref name="usfs"/><ref>[http://eol.org/pages/582277/hierarchy_entries/46207742/overview Integrated Taxonomic Information System (ITIS): ''Toxicodendron diversilobum'' (Western Poison-oak) - Overview]</ref> It reproduces by spreading [[rhizome]]s and by seeds.<ref name=Hogan/>


[[Image:PoisonOakGreenPhase.jpg|thumb|325px|Pacific Poison-oak foliage.]]
[[Image:PoisonOakGreenPhase.jpg|thumb|Pacific poison-oak foliage]]
The plant 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.
The plant 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.


The leaves are divided into three (''rarely 5, 7, or 9'') [[leaflets]], {{convert|3.5|to|10|cm|in}} long, with scalloped, toothed, or lobed edges.<ref name="jepson"/> They generally resemble the lobed leaves of a true oak, though the Pacific poison oak leaves will tend to be more glossy. Leaves are typically bronze when first unfolding in February to March, bright green in the Spring, yellow-green to reddish in the Summer, and bright red or pink from late July to October.<ref name="usfs"/>
The leaves are divided into three (rarely 5, 7, or 9) [[leaflets]], {{convert|3.5|to|10|cm|in}} long, with scalloped, toothed, or lobed edges.<ref name="jepson"/> They generally resemble the lobed leaves of a true oak, though the Pacific poison oak leaves will tend to be more glossy. Leaves are typically bronze when first unfolding in February to March, bright green in the spring, yellow-green to reddish in the summer, and bright red or pink from late July to October.<ref name="usfs"/>


White flowers form in the spring, from March to June.<ref name="usfs"/> If they are fertilized, they develop into greenish-white or tan berries.<ref name="jepson"/>
White flowers form in the spring, from March to June.<ref name="usfs"/> If they are fertilized, they develop into greenish-white or tan berries.<ref name="jepson"/>


Botanist John Howell observed the toxicity of ''Toxicodendron diversilobum'' obscures its merits:<br/>
Botanist John Howell observed the toxicity of ''Toxicodendron diversilobum'' obscures its merits:<br/>
::"In spring, the ivory flowers bloom on the sunny hill or in sheltered glade, in summer its fine green leaves contrast refreshingly with dried and tawny grassland, in autumn its colors flame more brilliantly than in any other native, but one great fault, its poisonous juice, nullifies its every other virtue and renders this beautiful shrub the most disparaged of all within our region."<ref>{{cite book | last = Howell | first = John Thomas | authorlink = | coauthors = Frank Almeda, Wilma Follette, Catherine Best | title = Marin Flora | publisher = California Academy of Sciences; California Native Plant Society | year = 2007 | location = | pages = 264 | url = | doi = | id = | isbn = }}</ref>
::"In spring, the ivory flowers bloom on the sunny hill or in sheltered glade, in summer its fine green leaves contrast refreshingly with dried and tawny grassland, in autumn its colors flame more brilliantly than in any other native, but one great fault, its poisonous juice, nullifies its every other virtue and renders this beautiful shrub the most disparaged of all within our region."<ref>{{cite book | author= John Thomas Howell, Frank Almeda, Wilma Follette & Catherine Best | title = Marin Flora | publisher = California Academy of Sciences; California Native Plant Society | year = 2007 | location = | pages = 264 |isbn=094022870X}}</ref>


===Toxin qualities===
===Toxin qualities===
{{main|Urushiol-induced contact dermatitis}}
{{main|Urushiol-induced contact dermatitis}}
Pacific poison oak leaves and twigs have a surface oil, [[urushiol]], which causes an [[allergy|allergic reaction]].<ref name=Hogan /> It causes contact dermatitis&nbsp;— an immune-mediated skin inflammation &nbsp;— in four-fifths of humans.<ref>Kalish, S., et al. "Processing of urushiol (poison ivy) hapten by both endogenous and exogenous pathways for presentation to T cells in vitro." (1994). JCI. Volume 93, no 5, pgs 2039–2047.</ref><ref>[http://mic-ro.com/plants/ Mic-ro.com: Contact-Poisonous Plants of the World<!-- Bot generated title -->]</ref> However, most, if not all, will become sensitized over time with repeated or more concentrated exposure to urushiol.
Pacific poison oak leaves and twigs have a surface oil, [[urushiol]], which causes an [[allergy|allergic reaction]].<ref name=Hogan /> It causes contact dermatitis&nbsp;– an immune-mediated skin inflammation&nbsp;– in four-fifths of humans.<ref>{{cite journal |author=R. S. Kalish, J. A. Wood & A. LaPorte |year=1994 |title=Processing of urushiol (poison ivy) hapten by both endogenous and exogenous pathways for presentation to T cells in vitro |journal=[[Journal of Clinical Investigation]] |volume=93 |issue=5 |pages=2039–2047 |pmid=7910172 |pmc=294319 |doi=}}</ref><ref>[http://mic-ro.com/plants/ Mic-ro.com: Contact-Poisonous Plants of the World<!-- Bot generated title -->]</ref> However, most, if not all, will become sensitized over time with repeated or more concentrated exposure to urushiol.


The active components of urushiol have been determined by to be unsaturated congeners of 3-heptadecylcatechol with up to three double bonds in an unbranched C17 side chain.<ref>Billets, S., Corbett, M. D. "Characterization of poison oak urushiol." (1975). Journal of Pharmaceutical Sciences. Volume 64, issue 10, pgs 1715–1718.</ref> In poison ivy, these components are unique in that they contain a -CH2CH2- group in an unbranched alkyl side chain.<ref name=Billets2>Billets, S., et al. "New GLC analysis of urushiol congeners in different plant parts of poison ivy, Toxicodendron radicans." (1978). JPS. Volume 67, issue 4, pgs 483–485.</ref>
The active components of urushiol have been determined by to be unsaturated congeners of 3-heptadecylcatechol with up to three double bonds in an unbranched C17 side chain.<ref>{{cite journal |author=Michael D. Corbett & Stephen Billets |year=1975 |title=Characterization of poison oak urushiol |journal=[[Journal of Pharmaceutical Sciences]] |volume=64 |issue=10 |pages=1715–1718 |doi=10.1002/jps.2600641032}}</ref> In poison ivy, these components are unique in that they contain a -CH2CH2- group in an unbranched alkyl side chain.<ref name=Billets2>{{cite journal |author=John C. Craig, Coy W. Waller, Stephen Billets & Mahmoud A. Elsohly |year=1978 |title=New GLC analysis of urushiol congeners in different plant parts of poison ivy, ''Toxicodendron radicans'' |journal=[[Journal of Pharmaceutical Sciences]] |volume=67 |issue=4 |pages=483–485 |doi=10.1002/jps.2600670411}}</ref>


====Reactions====
====Reactions====
[[File:Poison ivy contact dermatitis.jpg|thumb|150px|[[Urushiol-induced contact dermatitis]] from poison oak.]]
[[File:Poison ivy contact dermatitis.jpg|thumb|[[Urushiol-induced contact dermatitis]] from poison oak]]
Pacific poison oak skin contact first causes itching; then evolves into [[Urushiol-induced contact dermatitis|dermatitus]] with inflammation, colorless bumps, severe itching, and blistering.<ref>[http://poisonivy.aesir.com/view Poison Oak/Poison Ivy Information Center]</ref> In the dormant deciduous seasons the plant can be difficult to recognize, however leafless branches and twigs contact also causes allergic reactions.
Pacific poison oak skin contact first causes itching; then evolves into [[Urushiol-induced contact dermatitis|dermatitus]] with inflammation, colorless bumps, severe itching, and blistering.<ref>[http://poisonivy.aesir.com/view Poison Oak/Poison Ivy Information Center]</ref> In the dormant deciduous seasons the plant can be difficult to recognize, however leafless branches and twigs contact also causes allergic reactions.


Urushiol volatilizes when burned, and human exposure to ''Toxicodendron diversilobum'' smoke is extremely hazardous, from [[wildfire]]s, [[controlled burn]]s, or disposal fires.<ref name="usfs"/> The smoke can poison people who thought they were immune.<ref name="usfs"/> Branches used to toast food over campfires can cause reactions internally and externally, although the [[Karok]] peoples traditionally used them as a cooking tool.{{citation needed|date=October 2013}}
Urushiol volatilizes when burned, and human exposure to ''Toxicodendron diversilobum'' smoke is extremely hazardous, from [[wildfire]]s, [[controlled burn]]s, or disposal fires.<ref name="usfs"/> The smoke can poison people who thought they were immune.<ref name="usfs"/> Branches used to toast food over campfires can cause reactions internally and externally, although the [[Karok]] peoples traditionally used them as a cooking tool.{{citation needed|date=October 2013}}
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[[Black-tailed deer]], [[Mule deer]], [[California ground squirrel]]s, [[Western gray squirrel]]s, and other indigenous fauna feed on the leaves of the plant.<ref name="usfs"/> It is rich in phosphorus, calcium, and sulfur.<ref name="usfs"/> Bird species use the berries for food, and utilize the plant structure for shelter.<ref name="usfs"/> Neither native animals, nor horses, livestock, or canine pets, demonstrate reactions to urushiol.<ref name=Hogan/>
[[Black-tailed deer]], [[Mule deer]], [[California ground squirrel]]s, [[Western gray squirrel]]s, and other indigenous fauna feed on the leaves of the plant.<ref name="usfs"/> It is rich in phosphorus, calcium, and sulfur.<ref name="usfs"/> Bird species use the berries for food, and utilize the plant structure for shelter.<ref name="usfs"/> Neither native animals, nor horses, livestock, or canine pets, demonstrate reactions to urushiol.<ref name=Hogan/>


Due to human allergic reactions, Pacific poison oak plants are usually eradicated in [[garden]]s and public landscaped areas. It can be a [[weed]] in agricultural fields, orchards, and vineyards.<ref>[http://www.ipm.ucdavis.edu/PMG/WEEDS/pacific_poisonoak.html UC Integrated Pest Management Weed Photo Gallery and information (profile of this plant as an agricultural weed).]</ref> It is usually removed by pruning, [[herbicide]]s, digging out, or a combination of these.<ref>''Sunset Western Garden Book'' [5th edition], (Menlo Park: Sunset Publishing, 1988), p. 506</ref>
Due to human allergic reactions, Pacific poison oak plants are usually eradicated in [[garden]]s and public landscaped areas. It can be a [[weed]] in agricultural fields, orchards, and vineyards.<ref>[http://www.ipm.ucdavis.edu/PMG/WEEDS/pacific_poisonoak.html UC Integrated Pest Management Weed Photo Gallery and information (profile of this plant as an agricultural weed).]</ref> It is usually removed by pruning, [[herbicide]]s, digging out, or a combination of these.<ref>''Sunset Western Garden Book'' [5th edition], (Menlo Park: Sunset Publishing, 1988), p. 506</ref>


==Uses==
==Uses==


===Medicinal===
===Medicinal===
[[Indigenous peoples of California|Californian Native Americans]] used the plant's stems and shoots to make baskets, the sap to cure [[ringworm]], and as a [[poultice]] of fresh leaves applied to rattlesnake bites.<ref name="mich">[http://herb.umd.umich.edu/herb/search.pl?searchstring=Toxicodendron+diversilobum Univ. of Michigan, Dearborn —Native American Ethnobotany Database: ''Toxicodendron diversilobum'']</ref> The juice or soot was used as a black dye for [[Carex|sedge]] basket elements, tattoos, and skin darkening.<ref name="mich"/><ref>Conrad, C. Eugene. 1987. "Common shrubs of chaparral and associated ecosystems of southern California". Gen. Tech. Rep. PSW-99. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 86 p.</ref>
[[Indigenous peoples of California|Californian Native Americans]] used the plant's stems and shoots to make baskets, the sap to cure [[ringworm]], and as a [[poultice]] of fresh leaves applied to rattlesnake bites.<ref name="mich">[http://herb.umd.umich.edu/herb/search.pl?searchstring=Toxicodendron+diversilobum Univ. of Michigan, Dearborn – Native American Ethnobotany Database: ''Toxicodendron diversilobum'']</ref> The juice or soot was used as a black dye for [[Carex|sedge]] basket elements, tattoos, and skin darkening.<ref name="mich"/><ref>Conrad, C. Eugene. 1987. "Common shrubs of chaparral and associated ecosystems of southern California". Gen. Tech. Rep. PSW-99. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 86 p.</ref>


An [[infusion]] of dried roots, or buds eaten in the spring, were taken by some native peoples for an immunity from the plant poisons.<ref name="mich"/>
An [[infusion]] of dried roots, or buds eaten in the spring, were taken by some native peoples for an immunity from the plant poisons.<ref name="mich"/>


[[Chumash people]]s used Pacific poison-oak sap to remove warts, corns, and calluses; to cauterize sores; and to stop bleeding.<ref name="mich"/> They drank a [[decoction]] made from Pacific poison-oak roots to treat [[dysentery]].<ref>Timbrook, Jan. 1990. "Ethnobotany of Chumash Indians, California, based on collections by John P. Harrington". Economic Botany. 44(2): 236-253.</ref>
[[Chumash people]]s used Pacific poison-oak sap to remove warts, corns, and calluses; to cauterize sores; and to stop bleeding.<ref name="mich"/> They drank a [[decoction]] made from Pacific poison-oak roots to treat [[dysentery]].<ref>{{cite journal |author=Jan Timbrook |year=1990 |title=Ethnobotany of Chumash Indians, California, based on collections by John P. Harrington |journal=[[Economic Botany]] |volume=44 |issue=2 |pages=236–253 |jstor=4255231 |doi=10.1007/BF02860489}}</ref>


===Cultivation===
===Cultivation===
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==See also==
==See also==
*''[[Toxicodendron pubescens]]'' — Eastern poison oak
*''[[Toxicodendron pubescens]]'' – Eastern poison oak
*''[[Toxicodendron vernix]]'' — Poison sumac
*''[[Toxicodendron vernix]]'' – Poison sumac
*''[[Toxicodendron radicans]]'' — Eastern poison ivy
*''[[Toxicodendron radicans]]'' – Eastern poison ivy
*''[[Toxicodendron rydbergii]]'' — Western poison ivy
*''[[Toxicodendron rydbergii]]'' – Western poison ivy


==References==
==References==
{{Reflist}}
{{Reflist|32em}}
* [http://onlinelibrary.wiley.com/doi/10.1002/jps.2600641032/abstract Onlinelibrary.wiley.com: Abstract #1]
* [http://onlinelibrary.wiley.com/doi/10.1002/jps.2600670411/abstract Onlinelibrary.wiley.com: Abstract #2]

⚫
{{commons category|Toxicodendron diversilobum}}


==Gallery==
==Gallery==
<gallery>
<gallery>
⚫
Image:PoisonOakRedPhase.jpg|Red phase in spring

⚫
Image:PoisonOakRedPhase.jpg|Red phase in Spring.
File:Poison-oak-flowering.jpg|Green phase, and flowers
File:Poison-oak-flowering.jpg|Green phase, and flowers
Image:Toxicodendron_diversilobum_berries.jpg|Berries
Image:Toxicodendron_diversilobum_berries.jpg|Berries
Image:Pacific-Poison-Oak.jpg|Summer—Autumn turning color phase
Image:Pacific-Poison-Oak.jpg|Summer–autumn turning color phase
Image:PoisonOak wb smallerLeaves.jpg|Shrub form
Image:PoisonOak wb smallerLeaves.jpg|Shrub form
Image:ClimbingPoisonOak.jpg|Vine form
Image:ClimbingPoisonOak.jpg|Vine form
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==External links==
==External links==
{{commons category|Toxicodendron diversilobum}}
*[http://www.fs.fed.us/database/feis/plants/vine/toxdiv/all.html U.S. Forest Service information: ''Toxicodendron diversilobum'' (Pacific poison oak)]
*[http://www.fs.fed.us/database/feis/plants/vine/toxdiv/all.html U.S. Forest Service information: ''Toxicodendron diversilobum'' (Pacific poison oak)]
*[http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Toxicodendron+diversilobum Calflora Database: ''Toxicodendron diversilobum'' (Pacific poison oak)]
*[http://www.calflora.org/cgi-bin/species_query.cgi?where-taxon=Toxicodendron+diversilobum Calflora Database: ''Toxicodendron diversilobum'' (Pacific poison oak)]
*[http://www.plants.usda.gov/java/profile?symbol=todi USAD Plants profile for ''Toxicodendron diversilobum'' (western poison oak)]
*[http://www.plants.usda.gov/java/profile?symbol=todi USAD Plants profile for ''Toxicodendron diversilobum'' (western poison oak)]
*[http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=46791 Jepson Flora Project: ''Toxicodendron diversilobum'']
*[http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=46791 Jepson Flora Project: ''Toxicodendron diversilobum'']
*[http://www.aad.org/public/Publications/pamphlets/Poison_IvyOakSumac.htm American Academy of Dermatology&nbsp;— Poison Oak information]
*[http://www.aad.org/public/Publications/pamphlets/Poison_IvyOakSumac.htm American Academy of Dermatology&nbsp;– Poison Oak information]
*[http://www.hanskellner.com/photos/2004/05/PoisonOak/ Western Poison-Oak Photo Gallery]
*[http://www.hanskellner.com/photos/2004/05/PoisonOak/ Western Poison-Oak Photo Gallery]
*[http://calphotos.berkeley.edu/cgi/img_query?where-taxon=Toxicodendron+diversilobum ''Toxicodendron diversilobum'' — U.C. Photo gallery]
*[http://calphotos.berkeley.edu/cgi/img_query?where-taxon=Toxicodendron+diversilobum ''Toxicodendron diversilobum'' – U.C. Photo gallery]


[[Category:Toxicodendron|diversilobum]]
[[Category:Toxicodendron|diversilobum]]
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[[Category:Natural history of the Santa Monica Mountains]]
[[Category:Natural history of the Santa Monica Mountains]]
[[Category:Plants used in traditional Native American medicine]]
[[Category:Plants used in traditional Native American medicine]]
[[Category:Plants described in 1838]]

Version vom 16. November 2013, 10:12 Uhr

Vorlage:Merge from Vorlage:Italic title

Systematik

Toxicodendron diversilobum, commonly named Pacific poison oak or western poison oak (syn. Rhus diversiloba), is in the Anacardiaceae family (the sumac family).

The woody vine or shrub is widely distributed in western North America, inhabiting conifer and mixed broadleaf forests, woodlands, grasslands, and chaparral biomes.[1] It is known for causing itching and allergic rashes in many humans, after contact by touch or smoke inhalation.

Distribution

The Pacific poison-oak Toxicodendron species is found in California, the Baja California peninsula, Nevada, Oregon, Washington, and British Columbia.[2] The related eastern poison oak (Toxicodendron pubescens) is native to the Southeastern United States. Pacific poison-oak and western poison-ivy (Toxicodendron rydbergii) hybridize in the Columbia River Gorge area.[3]

Toxicodendron diversilobum is common in various habitats, from mesic riparian zones to xeric chaparral.[4] It thrives in shady and dappled light through full and direct sunlight conditions, at elevations below Vorlage:Convert.[3] The vining form can climb up large shrub and tree trunks into their canopies. Sometimes it kills the support plant by smothering or breaking it.[3]

The plant often occurs in chaparral and woodlands, coastal sage scrub, grasslands, and oak woodlands; and Douglas-fir (Pseudotsuga menzesii), hemlock–Sitka spruce, coast redwood (Sequoia sempervirens), yellow pine (Pinus ponderosa), and mixed evergreen forests.[5]

Description

Toxicodendron diversilobum, Pacific or western poison oak, is extremely variable in growth habit and leaf appearance. It grows as a dense Vorlage:Convert tall shrub in open sunlight, a treelike vine Vorlage:Convert and may be more than more than Vorlage:Convert long with an Vorlage:Convert trunk, as dense thickets in shaded areas, or any form in between [3][6] It reproduces by spreading rhizomes and by seeds.[1]

Pacific poison-oak foliage

The plant 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.

The leaves are divided into three (rarely 5, 7, or 9) leaflets, Vorlage:Convert long, with scalloped, toothed, or lobed edges.[4] They generally resemble the lobed leaves of a true oak, though the Pacific poison oak leaves will tend to be more glossy. Leaves are typically bronze when first unfolding in February to March, bright green in the spring, yellow-green to reddish in the summer, and bright red or pink from late July to October.[3]

White flowers form in the spring, from March to June.[3] If they are fertilized, they develop into greenish-white or tan berries.[4]

Botanist John Howell observed the toxicity of Toxicodendron diversilobum obscures its merits:

"In spring, the ivory flowers bloom on the sunny hill or in sheltered glade, in summer its fine green leaves contrast refreshingly with dried and tawny grassland, in autumn its colors flame more brilliantly than in any other native, but one great fault, its poisonous juice, nullifies its every other virtue and renders this beautiful shrub the most disparaged of all within our region."[7]

Toxin qualities

Pacific poison oak leaves and twigs have a surface oil, urushiol, which causes an allergic reaction.[1] It causes contact dermatitis – an immune-mediated skin inflammation – in four-fifths of humans.[8][9] However, most, if not all, will become sensitized over time with repeated or more concentrated exposure to urushiol.

The active components of urushiol have been determined by to be unsaturated congeners of 3-heptadecylcatechol with up to three double bonds in an unbranched C17 side chain.[10] In poison ivy, these components are unique in that they contain a -CH2CH2- group in an unbranched alkyl side chain.[11]

Reactions

Urushiol-induced contact dermatitis from poison oak

Pacific poison oak skin contact first causes itching; then evolves into dermatitus with inflammation, colorless bumps, severe itching, and blistering.[12] In the dormant deciduous seasons the plant can be difficult to recognize, however leafless branches and twigs contact also causes allergic reactions.

Urushiol volatilizes when burned, and human exposure to Toxicodendron diversilobum smoke is extremely hazardous, from wildfires, controlled burns, or disposal fires.[3] The smoke can poison people who thought they were immune.[3] Branches used to toast food over campfires can cause reactions internally and externally, although the Karok peoples traditionally used them as a cooking tool.Vorlage:Citation needed

Ecology

Black-tailed deer, Mule deer, California ground squirrels, Western gray squirrels, and other indigenous fauna feed on the leaves of the plant.[3] It is rich in phosphorus, calcium, and sulfur.[3] Bird species use the berries for food, and utilize the plant structure for shelter.[3] Neither native animals, nor horses, livestock, or canine pets, demonstrate reactions to urushiol.[1]

Due to human allergic reactions, Pacific poison oak plants are usually eradicated in gardens and public landscaped areas. It can be a weed in agricultural fields, orchards, and vineyards.[13] It is usually removed by pruning, herbicides, digging out, or a combination of these.[14]

Uses

Medicinal

Californian Native Americans used the plant's stems and shoots to make baskets, the sap to cure ringworm, and as a poultice of fresh leaves applied to rattlesnake bites.[15] The juice or soot was used as a black dye for sedge basket elements, tattoos, and skin darkening.[15][16]

An infusion of dried roots, or buds eaten in the spring, were taken by some native peoples for an immunity from the plant poisons.[15]

Chumash peoples used Pacific poison-oak sap to remove warts, corns, and calluses; to cauterize sores; and to stop bleeding.[15] They drank a decoction made from Pacific poison-oak roots to treat dysentery.[17]

Cultivation

Toxicodendron diversilobum can be a carefully sited component in wildlife gardens, habitat gardens, and natural landscaping.

The plant is used in habitat restoration projects.[3] It can be early stage succession where woodlands have been burned or removed, serving as a nurse plant for other species.

See also

References

Vorlage:Reflist

Gallery

  • Red phase in spring
    Red phase in spring
  • Green phase, and flowers
    Green phase, and flowers
  • Berries
    Berries
  • Summer–autumn turning color phase
    Summer–autumn turning color phase
  • Shrub form
    Shrub form
  • Vine form
    Vine form

External links

Vorlage:Commons category

  1. ↑ a b c d C. Michael Hogan (2008); "Western poison-oak: Toxicodendron diversilobum", GlobalTwitcher, ed. Nicklas Strömberg
  2. ↑ Vorlage:PLANTS
  3. ↑ a b c d e f g h i j k l U.S. Forest Service: Toxicodendron diversilobum
  4. ↑ a b c Jepson
  5. ↑ Calflora
  6. ↑ Integrated Taxonomic Information System (ITIS): Toxicodendron diversilobum (Western Poison-oak) - Overview
  7. ↑ John Thomas Howell, Frank Almeda, Wilma Follette & Catherine Best: Marin Flora. California Academy of Sciences; California Native Plant Society, 2007, ISBN 0-940228-70-X, S. 264.
  8. ↑ R. S. Kalish, J. A. Wood & A. LaPorte: Processing of urushiol (poison ivy) hapten by both endogenous and exogenous pathways for presentation to T cells in vitro. In: Journal of Clinical Investigation. 93. Jahrgang, Nr. 5, 1994, S. 2039–2047, PMID 7910172, PMC 294319 (freier Volltext).
  9. ↑ Mic-ro.com: Contact-Poisonous Plants of the World
  10. ↑ Michael D. Corbett & Stephen Billets: Characterization of poison oak urushiol. In: Journal of Pharmaceutical Sciences. 64. Jahrgang, Nr. 10, 1975, S. 1715–1718, doi:10.1002/jps.2600641032.
  11. ↑ John C. Craig, Coy W. Waller, Stephen Billets & Mahmoud A. Elsohly: New GLC analysis of urushiol congeners in different plant parts of poison ivy, Toxicodendron radicans. In: Journal of Pharmaceutical Sciences. 67. Jahrgang, Nr. 4, 1978, S. 483–485, doi:10.1002/jps.2600670411.
  12. ↑ Poison Oak/Poison Ivy Information Center
  13. ↑ UC Integrated Pest Management Weed Photo Gallery and information (profile of this plant as an agricultural weed).
  14. ↑ Sunset Western Garden Book [5th edition], (Menlo Park: Sunset Publishing, 1988), p. 506
  15. ↑ a b c d Univ. of Michigan, Dearborn – Native American Ethnobotany Database: Toxicodendron diversilobum
  16. ↑ Conrad, C. Eugene. 1987. "Common shrubs of chaparral and associated ecosystems of southern California". Gen. Tech. Rep. PSW-99. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 86 p.
  17. ↑ Jan Timbrook: Ethnobotany of Chumash Indians, California, based on collections by John P. Harrington. In: Economic Botany. 44. Jahrgang, Nr. 2, 1990, S. 236–253, doi:10.1007/BF02860489, JSTOR:4255231.
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