Toxicodendron
Encyclopedia
Toxicodendron a genus of flowering plant
s in the sumac
family, Anacardiaceae
. It contains woody
tree
s, shrub
s and vine
s, including poison ivy
, poison oak
, and the lacquer tree
. All members of the genus produce the skin-irritating oil urushiol
, which can cause a severe allergic
reaction. The generic name is derived from the Greek
words τοξικος (toxikos), meaning "poison," and δενδρον (dendron), meaning "tree."
Members of this genus are sometimes included in the genus Rhus
, although recent molecular evidence points to keeping Toxicodendron as a separate monophyletic
genus.
They have pinnate
ly compound, alternate leaves and whitish or grayish drupe
s. The best known members of the genus in North America
are poison ivy, practically ubiquitous throughout most of eastern North America, and poison oak, similarly ubiquitous throughout much of the western part of the continent.
The plants are quite variable in appearance. The leaves may have smooth, toothed or lobed edges, and all three types of leaf edge may be present in a single plant. The plants grow as creeping vines, climbing vines, shrubs, or, in the case of Lacquer Tree
and Poison Sumac
, as trees. While leaves of poison ivy and poison oaks usually have three leaflets, sometimes there are five or, occasionally, even seven leaflets. Leaves of Poison Sumac have 7–13 leaflets, and of Lacquer Tree, 7–19 leaflets.
The common names come from similar appearances to other species that are not closely related and to the allergic response to the urushiol. Poison oak is not an oak
(Quercus, family Fagaceae
), but this common name comes from the leaves' resemblance to white oak (Quercus alba) leaves, while Poison ivy is not an ivy
(Hedera, family Araliaceae
), but has a superficially similar growth form. Technically, the plants do not contain a poison
; they contain a potent allergen
.
The resin
s of certain species native to Japan
, China
and other Asia
n countries, such as T. vernicifluum (Lacquer Tree
) and T. succedaneum (Wax Tree), are used to make lacquer
, and, as a byproduct of lacquer manufacture, their berries are used to make japan wax
.
.
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s in the sumac
Sumac
Sumac is any one of approximately 250 species of flowering plants in the genus Rhus and related genera, in the family Anacardiaceae. Sumacs grow in subtropical and temperate regions throughout the world, especially in Africa and North America....
family, Anacardiaceae
Anacardiaceae
Anacardiaceae are a family of flowering plants bearing fruits that are drupes and in some cases producing urushiol, an irritant. Anacardiaceae include numerous genera with several of economic importance. Notable plants in this family include cashew , mango, poison ivy, sumac, smoke tree, and marula...
. It contains woody
Woody plant
A woody plant is a plant that uses wood as its structural tissue. These are typically perennial plants whose stems and larger roots are reinforced with wood produced adjacent to the vascular tissues. The main stem, larger branches, and roots of these plants are usually covered by a layer of...
tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s and vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...
s, including poison ivy
Poison ivy
Toxicodendron radicans, better known as poison ivy , is a poisonous North American plant that is well known for its production of urushiol, a clear liquid compound found within the sap of the plant that causes an itching rash in most people who touch it...
, poison oak
Poison oak
Poison oak may refer to* Toxicodendron diversilobum, grows on West Coast of North America* Toxicodendron pubescens, grows in the Eastern United Statesdamnnnnn tissss is terribleee...
, and the lacquer tree
Lacquer Tree
Toxicodendron vernicifluum , also known with the common name Chinese lacquer tree, is a species of genus Toxicodendron that grows in East Asia, in regions of China, Korea and Japan...
. All members of the genus produce the skin-irritating oil urushiol
Urushiol
Urushiol is an oily organic allergen found in plants of the family Anacardiaceae, especially Toxicodendron spp. . It causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis...
, which can cause a severe allergic
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
reaction. The generic name is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
words τοξικος (toxikos), meaning "poison," and δενδρον (dendron), meaning "tree."
Members of this genus are sometimes included in the genus Rhus
Sumac
Sumac is any one of approximately 250 species of flowering plants in the genus Rhus and related genera, in the family Anacardiaceae. Sumacs grow in subtropical and temperate regions throughout the world, especially in Africa and North America....
, although recent molecular evidence points to keeping Toxicodendron as a separate monophyletic
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
genus.
They have pinnate
Pinnate
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
ly compound, alternate leaves and whitish or grayish drupe
Drupe
In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
s. The best known members of the genus in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
are poison ivy, practically ubiquitous throughout most of eastern North America, and poison oak, similarly ubiquitous throughout much of the western part of the continent.
The plants are quite variable in appearance. The leaves may have smooth, toothed or lobed edges, and all three types of leaf edge may be present in a single plant. The plants grow as creeping vines, climbing vines, shrubs, or, in the case of Lacquer Tree
Lacquer Tree
Toxicodendron vernicifluum , also known with the common name Chinese lacquer tree, is a species of genus Toxicodendron that grows in East Asia, in regions of China, Korea and Japan...
and Poison Sumac
Poison Sumac
Poison sumac is a woody shrub or small tree growing to 7 m tall. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans...
, as trees. While leaves of poison ivy and poison oaks usually have three leaflets, sometimes there are five or, occasionally, even seven leaflets. Leaves of Poison Sumac have 7–13 leaflets, and of Lacquer Tree, 7–19 leaflets.
The common names come from similar appearances to other species that are not closely related and to the allergic response to the urushiol. Poison oak is not an oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
(Quercus, family Fagaceae
Fagaceae
The family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like nuts. Fagaceous leaves are often...
), but this common name comes from the leaves' resemblance to white oak (Quercus alba) leaves, while Poison ivy is not an ivy
Ivy
Ivy, plural ivies is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and across central-southern Asia east to Japan and Taiwan.-Description:On level ground they...
(Hedera, family Araliaceae
Araliaceae
Araliaceae is a family of flowering plants, also known as the Aralia family or Ivy family. The family includes 254 species of trees, shrubs, lianas and perennial herbaceous plants into 2 subfamilies...
), but has a superficially similar growth form. Technically, the plants do not contain a poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
; they contain a potent allergen
Allergen
An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
.
The resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
s of certain species native to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and other Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
n countries, such as T. vernicifluum (Lacquer Tree
Lacquer Tree
Toxicodendron vernicifluum , also known with the common name Chinese lacquer tree, is a species of genus Toxicodendron that grows in East Asia, in regions of China, Korea and Japan...
) and T. succedaneum (Wax Tree), are used to make lacquer
Lacquer
In a general sense, lacquer is a somewhat imprecise term for a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required...
, and, as a byproduct of lacquer manufacture, their berries are used to make japan wax
Japan wax
Japan wax is a pale-yellow, waxy, water-insoluble solid with a gummy feel, obtained from the berries of certain sumacs native to Japan and China, such as Rhus verniciflua and R. succedanea ....
.
Avoidance, treatment, and safety
For specific information on prevention and treatment of Toxicodendron rashes, see Urushiol-induced contact dermatitisUrushiol-induced contact dermatitis
Urushiol-induced contact dermatitis is the medical name given to allergic rashes produced by the oil urushiol, which is contained in various plants, including the plants of the genus Toxicodendron , other plants in the family Anacardiaceae Urushiol-induced contact dermatitis (also called...
.
Selected species of Toxicodendron
- Toxicodendron acuminatum (or Rhus acuminata) grows in ChinaChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, BhutanBhutanBhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...
, IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and NepalNepalNepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
.
- Western Poison oak (Toxicodendron diversilobum or Rhus diversiloba) is found throughout much of western North AmericaNorth AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, ranging from the Pacific coastPacific CoastA country's Pacific coast is the part of its coast bordering the Pacific Ocean.-The Americas:Countries on the western side of the Americas have a Pacific coast as their western border.* Geography of Canada* Geography of Chile* Geography of Colombia...
into the Sierra Nevada and Cascade mountain rangeMountain rangeA mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
s between southern British ColumbiaBritish ColumbiaBritish Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
and southward into Baja California. It is extremely common in that region, where it is the predominant species of the genus. Indeed, it is California's most prevalent woody shrub. Extremely variable, it grows as a dense shrub in open sunlight, or as a climbing vine in shaded areas. It propagates by creeping rhizomeRhizomeIn botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
s or by seed. The compound leaves are divided into three leaflets, 35–100 mm long, with scalloped, toothed, or lobed edges. Californians learn to recognize it by the rhyme "leaves of three, let it be". The leaves may be red, yellow, green, or some combination of those colors, depending on various factors, such as the time of year.
- Asian Poison ivy (Toxicodendron orientale, Rhus orientale or R. ambigua) is very similar to the American Poison ivy, and replaces it throughout east Asia (so similar that some texts treat it as just a variety of the American species).
- Toxicodendron parviflorum (or Rhus parviflora).
- Potanin's Lacquer Tree or Chinese Varnish Tree (Toxicodendron potaninii or Rhus potaninii) from central China, is similar to T. vernicifluum but with (usually) fewer leaflets per leaf. Growing up to 20 m tall, like T. vernicifluum it is used for lacquerLacquerIn a general sense, lacquer is a somewhat imprecise term for a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required...
production. The leaves have 7–9 leaflets.
- Atlantic Poison oak (Toxicodendron pubescens or Rhus toxicarium) grows mostly in sandy soils in eastern parts of the United States. Growing as a shrub, its leaves are in groups of three. Leaves are typically rounded or lobed, and are densely haired. Although it is often confused with the more common poison ivy, even in the scientific literature, Atlantic Poison oak has small clumps of hair on the veins on the underside of the leaves, while Poison ivy does not.
- Poison ivy (Toxicodendron radicans or Rhus radicans) is extremely common in some areas of North America. In the United States it grows in all states east of the Rockies except North Dakota. It also grows in Central America. Appearing as a creeping vine, a climbing vine, or a shrub, it reproduces both by creeping rootstocks and by seeds. The appearance varies. Leaves, arranged in an alternate pattern, usually in groups of three, are from 20 to 50 mm long, pointed at the tip, and may be toothed, smooth, or lobed, but never serrated. Leaves may be shiny or dull, and the color varies with the season. Vines grow almost straight up rather than wrapping around their support, and can grow to 8–10 m in height. In some cases, Poison ivy may entirely engulf the supporting structure, and vines may extend outward like limbs, so that it appears to be a Poison ivy "tree".
- Western Poison ivy (Toxicodendron rydbergii or Rhus rydbergii) is found in northern parts of the eastern United States. It also exists in the western United States and Canada, but is much less common than Poison oak. It may grow as a vine or a shrub. It was once considered a subspecies of Poison ivy. It does sometimes hybridize with the climbing species. Western Poison ivy is found in much of western and central United States and Canada, although not on the West Coast. In the eastern United States it is rarely found south of New England.
- Manzanillo (Toxicodendron striatumToxicodendron striatumToxicodendron striatum is a South American poisonous tree in the Anacardiaceae family, commonly called Manzanillo. T. striatum grows in the tropical rain forests on low elevation slopes.- External links :*...
or Rhus striata) is a South AmericaSouth AmericaSouth America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
n poisonous tree growing in the tropical rain forests on low elevation slopes.
- Wax Tree (Toxicodendron succedaneum or Rhus succedanea), a native of Asia, although it has been planted elsewhere, most notably Australia and New Zealand. It is a large shrub or tree, up to 8 m tall, somewhat similar to a sumac tree. Because of its beautiful autumn foliage, it has been planted outside of Asia as an ornamental plantOrnamental plantOrnamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display...
, often by gardeners who were apparently unaware of the dangers of allergic reactions. It is now officially classified as a noxious weed in Australia and New Zealand. The fatty-acid methyl ester of the kernel oil meets all of the major biodieselBiodieselBiodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
requirements in the USA (ASTM D 6751-02, ASTM PS 121-99), Germany (DIN V 51606) and European Union (EN 14214).
- Toxicodendron sylvestre (or Rhus sylvestris) grows in ChinaChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, KoreaKoreaKorea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
and TaiwanTaiwanTaiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
.
- Lacquer TreeLacquer TreeToxicodendron vernicifluum , also known with the common name Chinese lacquer tree, is a species of genus Toxicodendron that grows in East Asia, in regions of China, Korea and Japan...
or Varnish Tree (Toxicodendron vernicifluum or Rhus verniciflua) grows in Asia, especially China and Japan. Growing up to 20 m tall, its sap produces an extremely durable lacquerLacquerIn a general sense, lacquer is a somewhat imprecise term for a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required...
. The leaves have 7–19 leaflets (most often 11–13). The sap contains the allergenic oil, urushiol. Urushiol gets its name from this species which in JapaneseJapanese languageis a language spoken by over 130 million people in Japan and in Japanese emigrant communities. It is a member of the Japonic language family, which has a number of proposed relationships with other languages, none of which has gained wide acceptance among historical linguists .Japanese is an...
is called Urushi. Other names for this species include Japanese lacquer tree, Japanese Varnish Tree and Japanese Sumac (Note: the term "varnish tree" is also occasionally applied to the CandlenutCandlenutAleurites moluccana, the Candlenut, is a flowering tree in the spurge family, Euphorbiaceae, also known as Candleberry, Indian walnut, Kemiri, Varnish tree, Nuez de la India, Buah keras or Kukui nut tree....
, Aleurites moluccana, a southeast Asian tree unrelated to Toxicodendron).
- Poison SumacPoison SumacPoison sumac is a woody shrub or small tree growing to 7 m tall. All parts of the plant contain a resin called urushiol that causes skin and mucous membrane irritation to humans...
(Toxicodendron vernix or Rhus vernix) is a tall shrub or a small tree, from 2–7 m tall. It is found in swampy, open areas and reproduces by seeds. The leaves have between 7–13 untoothed leaflets, in a feather-compoundPinnatePinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna meaning "feather", "wing", or "fin". A similar term is pectinate, which refers to a comb-like arrangement of parts...
arrangement. In terms of its potential to cause urushiol-induced contact dermatitisUrushiol-induced contact dermatitisUrushiol-induced contact dermatitis is the medical name given to allergic rashes produced by the oil urushiol, which is contained in various plants, including the plants of the genus Toxicodendron , other plants in the family Anacardiaceae Urushiol-induced contact dermatitis (also called...
, poison sumac is far more virulent than other Toxicodendron species, even more virulent than poison ivy and poison oak. According to some botanists, poison sumac (Toxicodendron vernix) is the most toxicToxinA toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
plant species in the United States (Frankel, 1991).