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{{Taxobox
| color = lightgreen
| name = Poison ivy
| image = Poison_ivy_lg.jpg
| image_width = 240px
| regnum = [[Plant]]ae
| phylum = [[Flowering plant|Magnoliophyta]]
| classis = [[Dicotyledon|Magnoliopsida]]
| ordo = [[Sapindales]]
| familia = [[Anacardiaceae]]
| genus = ''[[Toxicodendron]]''
| species = '''''T. radicans'''''
| binomial = ''Toxicodendron radicans''
| binomial_authority = ([[Carolus Linnaeus|L.]]) [[Otto Kuntze|Kuntze]]
}}
'''Poison ivy''' (''Toxicodendron radicans'' or ''Rhus toxicodendron'') is a plant in the family [[Anacardiaceae]]. The name is often spelled "Poison-ivy" to indicate that it is not a true [[Ivy]] or ''Hedera''. It is a [[wood]]y [[vine]] that is well-known for its ability to produce [[urushiol]], a skin irritant that causes an itching rash for most people, technically known as [[urushiol-induced contact dermatitis]]. In extreme cases, [[corticosteroids]] can be used to treat rashes.
==Habitat and range==
Poison ivy grows vigorously throughout much of [[North America]]. It can grow as a shrub up to about 1.2 meters (4 ft) tall, as a [[groundcover]] 10-25 centimeters (4-10 in) high, or as a climbing vine on various supports. Older vines on substantial supports send out lateral branches that may at first be mistaken for tree limbs.
Poison ivy is apparently far more common now than when the [[Europe]]ans first entered North America because it has profited immensely from the "[[edge effect]]", enabling it to form lush colonies in such places.
Poison ivy (and [[Poison oak|oak]]) rarely grow at altitudes above 1500 metres (5,000 ft).
==Effects on the body==
The reaction caused by poison ivy, [[urushiol-induced contact dermatitis]], is an [[allergy|allergic reaction]]. For this reason some people do not respond to the "poison" because they simply do not have an allergy to urushiol. Around 15%<ref>[http://science.howstuffworks.com/poison-ivy.htm]</ref> to 30%<ref>[http://mic-ro.com/plants/]</ref> of people are immune to the effects; however, sensitivity can develop over time. For those who are affected by it, it causes a very irritating rash. If poison ivy is burned and the smoke then inhaled, this rash will appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty. If poison ivy is eaten, the digestive tract and airways will be affected, in some cases causing death.
Urushiol oil can remain viable on dead poison ivy plants and other surfaces for up to five years and will cause the same effect.{{Fact|date=February 2007}}
==Characteristic appearance==
The [[Leaf|leaves]] are compound with three [[almond]]-shaped leaflets, giving rise to the [[mnemonic]], "Leaves of three, let it be". The [[berries]] (actually [[drupe]]s) are a grayish-white color and are a favorite winter food of some birds.
The color ranges from light green (usually the younger leaves) to dark green (mature leaves), turning bright red in [[Autumn|fall]]. The leaflets are 3-12 cm long, rarely up to 30 cm. Each leaflet has a few or no teeth along its edge, and the leaf surface is smooth. To compare, [[blackberry]] and [[raspberry]] leaves also come in threes, but they have many teeth along the leaf edge, and the top surface of their leaves are very wrinkled where the veins are. The stem and vine are brown and woody, while blackberry stems are green with thorns.
[[Image:Poisonivyflowers1.jpg|left|thumb|220px|Poison ivy flowers]]
===Confusion with other plants===
*[[Virginia creeper]] (''Parthenocissus quinquefolia'') vine can look like poison ivy. The younger leaves can come in groups of three but have a few more serrations along the leaf edge, and the leaf surface is somewhat wrinkled. Virginia creeper and poison ivy very often grow together, even on the same tree.
*[[Western Poison-oak]] leaves also come in threes on the end of a stem, but each leaf is shaped somewhat like an [[oak]] leaf. Western Poison-oak only grows in the western United States, although many people will refer to poison ivy as poison-oak. This is because
poison ivy will grow in either the ivy-like form or the brushy oak-like form depending on the moisture and brightness of its environment. The ivy form likes shady areas with only a little sun, and tends to climb the trunks of trees, and can spread rapidly along the ground.
*[[Poison Sumac]]
*[[Blackberry]] vines bear a passing resemblance to poison ivy, with whose climates they overlap. The chief difference with blackberry vines is that they have spines on them, whereas poison ivy is smooth. Also, the three-leaf pattern of the leaves changes as the plant grows: the two bottom leaves both split into two leaves, for a total of five in a cluster.
*The thick vines of [[Vitis riparia|grape]], with no rootlets visible, differ from the vines of poison ivy, which have so many rootlets that the stem going up a tree looks furry.
==Use in homeopathy==
Dilute forms of Rhus toxicodendrom are used in [[homeopathic]] medicine most often as a remedy for [[musculoskeletal]] complaints with progressive stiffness that are worse with cold, wet, or inactivity, and better with motion, warmth, and use. The patient may have a red tip of the tongue or a red triangle on the tongue, [[herpes|herpetic]] outbreaks, and itchiness better with very hot water. The patient is joking and cheerful, very restless, and may be superstitious. <ref>{{cite book
| last = Morrsion, MD
| first = Roger
| title = Desktop guide to keynotes and comfirmatory symptoms
| publisher =Hahnemann Clinic Publishing
| date = 1993
| location =Grass Valley, CA
| pages = 323-327
| ISBN =0-9635368-0-X}}</ref>
.
==See also==
*[[Toxicodendron]] - an overview of plants with characteristics like poison ivy.
*[[Urushiol]], poison ivy's [[toxin]]
*[[Burow's solution]], for treating poison ivy injuries
*[[Poison Oak]]
*[[Poison Sumac]]
*[[Bentoquatam]]
==References==
<references/>
==External links==
{{commons|Rhus radicans}}
*[http://science.howstuffworks.com/poison-ivy.htm How Stuff Works: Poison ivy]
*[http://www.cattail.nu/ivy/ivy_index.html The Poison ivy tutorial]
*[http://mic-ro.com/plants/ Contact-Poisonous Plants of the World]
*[http://www.drgreene.org/body.cfm?id=21&action=detail&ref=559 Treating Poison ivy, Poison-oak, or Poison Sumac]
*[http://paipm.cas.psu.edu/pivy.html Poison ivy myths]
*[http://www.lib.uiowa.edu/hardin/md/poisonivypictures.html Links to pictures (Hardin MD/Univ of Iowa)]
*[http://www.poison-ivy.org photos and stories]
*[http://www.cas.vanderbilt.edu/bioimages/species/frame/tora2.htm ''Toxicodendron radicans'' images at bioimages.vanderbilt.edu]
*[http://waynesword.palomar.edu/ww0802.htm Poison Oak] at ''Wayne's Word''
[[Category:Sapindales]]
[[Category:Medicinal plants]]
[[Category:Poisonous plants]]
| color = lightgreen
| name = Poison ivy
| image = Poison_ivy_lg.jpg
| image_width = 240px
| regnum = [[Plant]]ae
| phylum = [[Flowering plant|Magnoliophyta]]
| classis = [[Dicotyledon|Magnoliopsida]]
| ordo = [[Sapindales]]
| familia = [[Anacardiaceae]]
| genus = ''[[Toxicodendron]]''
| species = '''''T. radicans'''''
| binomial = ''Toxicodendron radicans''
| binomial_authority = ([[Carolus Linnaeus|L.]]) [[Otto Kuntze|Kuntze]]
}}
'''Poison ivy''' (''Toxicodendron radicans'' or ''Rhus toxicodendron'') is a plant in the family [[Anacardiaceae]]. The name is often spelled "Poison-ivy" to indicate that it is not a true [[Ivy]] or ''Hedera''. It is a [[wood]]y [[vine]] that is well-known for its ability to produce [[urushiol]], a skin irritant that causes an itching rash for most people, technically known as [[urushiol-induced contact dermatitis]]. In extreme cases, [[corticosteroids]] can be used to treat rashes.
==Habitat and range==
Poison ivy grows vigorously throughout much of [[North America]]. It can grow as a shrub up to about 1.2 meters (4 ft) tall, as a [[groundcover]] 10-25 centimeters (4-10 in) high, or as a climbing vine on various supports. Older vines on substantial supports send out lateral branches that may at first be mistaken for tree limbs.
Poison ivy is apparently far more common now than when the [[Europe]]ans first entered North America because it has profited immensely from the "[[edge effect]]", enabling it to form lush colonies in such places.
Poison ivy (and [[Poison oak|oak]]) rarely grow at altitudes above 1500 metres (5,000 ft).
==Effects on the body==
The reaction caused by poison ivy, [[urushiol-induced contact dermatitis]], is an [[allergy|allergic reaction]]. For this reason some people do not respond to the "poison" because they simply do not have an allergy to urushiol. Around 15%<ref>[http://science.howstuffworks.com/poison-ivy.htm]</ref> to 30%<ref>[http://mic-ro.com/plants/]</ref> of people are immune to the effects; however, sensitivity can develop over time. For those who are affected by it, it causes a very irritating rash. If poison ivy is burned and the smoke then inhaled, this rash will appear on the lining of the lungs, causing extreme pain and possibly fatal respiratory difficulty. If poison ivy is eaten, the digestive tract and airways will be affected, in some cases causing death.
Urushiol oil can remain viable on dead poison ivy plants and other surfaces for up to five years and will cause the same effect.{{Fact|date=February 2007}}
==Characteristic appearance==
The [[Leaf|leaves]] are compound with three [[almond]]-shaped leaflets, giving rise to the [[mnemonic]], "Leaves of three, let it be". The [[berries]] (actually [[drupe]]s) are a grayish-white color and are a favorite winter food of some birds.
The color ranges from light green (usually the younger leaves) to dark green (mature leaves), turning bright red in [[Autumn|fall]]. The leaflets are 3-12 cm long, rarely up to 30 cm. Each leaflet has a few or no teeth along its edge, and the leaf surface is smooth. To compare, [[blackberry]] and [[raspberry]] leaves also come in threes, but they have many teeth along the leaf edge, and the top surface of their leaves are very wrinkled where the veins are. The stem and vine are brown and woody, while blackberry stems are green with thorns.
[[Image:Poisonivyflowers1.jpg|left|thumb|220px|Poison ivy flowers]]
===Confusion with other plants===
*[[Virginia creeper]] (''Parthenocissus quinquefolia'') vine can look like poison ivy. The younger leaves can come in groups of three but have a few more serrations along the leaf edge, and the leaf surface is somewhat wrinkled. Virginia creeper and poison ivy very often grow together, even on the same tree.
*[[Western Poison-oak]] leaves also come in threes on the end of a stem, but each leaf is shaped somewhat like an [[oak]] leaf. Western Poison-oak only grows in the western United States, although many people will refer to poison ivy as poison-oak. This is because
poison ivy will grow in either the ivy-like form or the brushy oak-like form depending on the moisture and brightness of its environment. The ivy form likes shady areas with only a little sun, and tends to climb the trunks of trees, and can spread rapidly along the ground.
*[[Poison Sumac]]
*[[Blackberry]] vines bear a passing resemblance to poison ivy, with whose climates they overlap. The chief difference with blackberry vines is that they have spines on them, whereas poison ivy is smooth. Also, the three-leaf pattern of the leaves changes as the plant grows: the two bottom leaves both split into two leaves, for a total of five in a cluster.
*The thick vines of [[Vitis riparia|grape]], with no rootlets visible, differ from the vines of poison ivy, which have so many rootlets that the stem going up a tree looks furry.
==Use in homeopathy==
Dilute forms of Rhus toxicodendrom are used in [[homeopathic]] medicine most often as a remedy for [[musculoskeletal]] complaints with progressive stiffness that are worse with cold, wet, or inactivity, and better with motion, warmth, and use. The patient may have a red tip of the tongue or a red triangle on the tongue, [[herpes|herpetic]] outbreaks, and itchiness better with very hot water. The patient is joking and cheerful, very restless, and may be superstitious. <ref>{{cite book
| last = Morrsion, MD
| first = Roger
| title = Desktop guide to keynotes and comfirmatory symptoms
| publisher =Hahnemann Clinic Publishing
| date = 1993
| location =Grass Valley, CA
| pages = 323-327
| ISBN =0-9635368-0-X}}</ref>
.
==See also==
*[[Toxicodendron]] - an overview of plants with characteristics like poison ivy.
*[[Urushiol]], poison ivy's [[toxin]]
*[[Burow's solution]], for treating poison ivy injuries
*[[Poison Oak]]
*[[Poison Sumac]]
*[[Bentoquatam]]
==References==
<references/>
==External links==
{{commons|Rhus radicans}}
*[http://science.howstuffworks.com/poison-ivy.htm How Stuff Works: Poison ivy]
*[http://www.cattail.nu/ivy/ivy_index.html The Poison ivy tutorial]
*[http://mic-ro.com/plants/ Contact-Poisonous Plants of the World]
*[http://www.drgreene.org/body.cfm?id=21&action=detail&ref=559 Treating Poison ivy, Poison-oak, or Poison Sumac]
*[http://paipm.cas.psu.edu/pivy.html Poison ivy myths]
*[http://www.lib.uiowa.edu/hardin/md/poisonivypictures.html Links to pictures (Hardin MD/Univ of Iowa)]
*[http://www.poison-ivy.org photos and stories]
*[http://www.cas.vanderbilt.edu/bioimages/species/frame/tora2.htm ''Toxicodendron radicans'' images at bioimages.vanderbilt.edu]
*[http://waynesword.palomar.edu/ww0802.htm Poison Oak] at ''Wayne's Word''
[[Category:Sapindales]]
[[Category:Medicinal plants]]
[[Category:Poisonous plants]]
