Toxicodendron diversilobum Pacific poison oak | |
---|---|
Pacific poison oak (larger and reddish leaves) at the base of an oak tree | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Sapindales |
Family: | Anacardiaceae |
Genus: | Toxicodendron |
Species: | T. diversilobum |
Binomial name | |
Toxicodendron diversilobum | |
Synonyms | |
Rhus diversilobaTorr. & A.Gray |
Toxicodendron diversilobum (syn. Rhus diversiloba), commonly named Pacific poison oak [1] or western poison oak, is a woody vine or shrub in the sumac family, Anacardiaceae.
It is widely distributed in western North America, inhabiting conifer and mixed broadleaf forests, woodlands, grasslands, and chaparral biomes. [2] Peak flowering occurs in May. [3] Like other members of the genus Toxicodendron , T. diversilobum causes itching and allergic rashes in most people after contact by touch or smoke inhalation. Despite its name, it is not closely related to oaks, nor is it a true tree.
Toxicodendron diversilobum is extremely variable in growth habit and leaf appearance. It grows as a dense 0.5–4 metres (1+1⁄2–13 feet) tall shrub in open sunlight, a treelike vine 3–9 m (10–30 ft) and may be more than 30 m (100 ft) long with an 8–20 centimetres (3+1⁄4–7+3⁄4 inches) trunk, as dense thickets in shaded areas, or any form in between. [4] [5] It reproduces by spreading rhizomes and by seeds. [2]
The plant is winter deciduous, so that after cold weather sets in, the stems are leafless and bear only the occasional cluster of mature fruit. Without leaves the 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, 3.5 to 10 cm (1+1⁄2 to 4 in) long, with scalloped, toothed, or lobed edges. [6] They generally resemble the lobed leaves of a true oak, though 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. [4]
White flowers form in the spring, from March to June. [4] If they are fertilized, they develop into greenish-white or tan drupes. [6]
Botanist John Howell observed that the plant's toxicity obscures its aesthetic values:
Toxicodendron diversilobum is found in California (Los Angeles was built on the site of a village named Yaangna or iyáanga’, meaning "poison oak place" [8] ), the Baja California Peninsula, Nevada, Oregon, Washington, and British Columbia. [9] The related T. pubescens (eastern poison oak) is native to the Southeastern United States. T. diversilobum and T. rydbergii (western poison ivy) hybridize in the Columbia River Gorge area. [4]
Toxicodendron diversilobum is common in various habitats, from mesic riparian zones to xeric chaparral. [6] It thrives in shady and dappled light through full and direct sunlight conditions, at elevations below 1,500 m (5,000 ft). [4] 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. [4] The plant often occurs in chaparral and woodlands, coastal sage scrub, grasslands, and oak woodlands; and Douglas-fir (Pseudotsuga menzesii), hemlock–Sitka spruce, Sequoia sempervirens (coast redwood), Pinus ponderosa (Ponderosa pine), and mixed evergreen forests. [10]
Black-tailed deer, mule deer, California ground squirrels, western gray squirrels, and other indigenous fauna feed on the leaves of the plant. [4] It is rich in phosphorus, calcium, and sulfur. [4] Bird species use the berries for food, and utilize the plant structure for shelter. [4] Neither native animals nor horses, livestock, or dogs demonstrate reactions to urushiol. [2]
Due to human allergic reactions, T. diversilobum is usually eradicated from gardens and public landscaped areas. It can be a weed in agricultural fields, orchards, and vineyards. [11] It is usually removed by pruning, herbicides, digging out, or a combination. [12] Poison oak is susceptible to infection by Phytophthora ramorum . [13]
Toxicodendron diversilobum leaves and twigs have a surface oil, urushiol, which causes an allergic reaction. [2] It causes contact dermatitis – an immune-mediated skin inflammation – in four-fifths of humans. [14] [15] 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 to be unsaturated congeners of 3-heptadecylcatechol with up to three double bonds in an unbranched C17 side chain. [16] In poison ivy, these components are unique in that they contain a -CH2CH2- group in an unbranched alkyl side chain. [17]
Toxicodendron diversilobum skin contact first causes itching; then evolves into dermatitis with inflammation, colorless bumps, severe itching, and blistering. [18] In the dormant deciduous seasons the plant can be difficult to recognize, however contact with leafless branches and twigs also causes allergic reactions.
Urushiol volatilizes when burned, and human exposure to T. diversilobum smoke is extremely hazardous, from wildfires, controlled burns, or disposal fires. [4] The smoke can poison people who thought they were immune. [4] Branches used to toast food over campfires can cause reactions internally and externally.
Urushiol is also found in the skin of mangos, posing a danger to people sensitized to T. diversilobum when eating the fruit while it is still in the rind. [19] [20]
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. [21] The juice or soot was used as a black dye for sedge basket elements, tattoos, and skin darkening. [21] [22]
An infusion of dried roots, or buds eaten in the spring, were taken by some native peoples[ which? ] for an immunity from the plant poisons. [21]
Chumash peoples used T. diversilobum sap to remove warts, corns, and calluses; to cauterize sores; and to stop bleeding. [21] They drank a decoction made from the roots to treat dysentery. [23]
Toxicodendron diversilobum can be a carefully situated component in wildlife gardens, habitat gardens, and natural landscaping.
The plant is used in habitat restoration projects. [4] It can be early stage succession where woodlands have been burned or removed, serving as a nurse plant for other species.
Toxicodendron is a genus of flowering plants in the sumac family, Anacardiaceae. It contains trees, shrubs and woody vines, 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 τοξικός (toxikos), meaning "poison," and δένδρον (dendron), meaning "tree". The best known members of the genus in North America are poison ivy (T. radicans), practically ubiquitous throughout most of eastern North America, and western poison oak, similarly ubiquitous throughout much of the western part of the continent.
Toxicodendron radicans, commonly known as eastern poison ivy or poison ivy, is an allergenic flowering plant that occurs in Asia and eastern North America. The species is well known for causing urushiol-induced contact dermatitis, an itchy, irritating, and sometimes painful rash, in most people who touch it. The rash is caused by urushiol, a clear liquid compound in the plant's sap. The species is variable in its appearance and habit, and despite its common name, it is not a true ivy (Hedera), but rather a member of the cashew and pistachio family (Anacardiaceae). T. radicans is commonly eaten by many animals and the seeds are consumed by birds, but poison ivy is most often thought of as an unwelcome weed. It is a different species from western poison ivy, T. rydbergii, which has similar effects.
Urushiol is an oily mixture of organic compounds with allergenic properties found in plants of the family Anacardiaceae, especially Toxicodendronspp., Comocladia spp. (maidenplums), Metopium spp. (poisonwood), and also in parts of the mango tree as well as the fruit of the cashew tree.
Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are not contagious or life-threatening, but can be very uncomfortable.
The Northern California coastal forests are a temperate coniferous forests ecoregion of coastal Northern California and southwestern Oregon.
Toxicodendron vernix, commonly known as poison sumac, or swamp-sumach, is a woody shrub or small tree growing to 9 metres (30 feet) tall. It was previously known as Rhus vernix. This plant is also known as thunderwood, particularly where it occurs in the southern United States.
Urushiol-induced contact dermatitis is a type of allergic contact dermatitis caused by the oil urushiol found in various plants, most notably sumac family species of the genus Toxicodendron: poison ivy, poison oak, poison sumac, and the Chinese lacquer tree. The name is derived from the Japanese word for the sap of the Chinese lacquer tree, urushi. Other plants in the sumac family also contain urushiol, as do unrelated plants such as Ginkgo biloba.
Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is within the California chaparral and woodlands ecoregion, of the Mediterranean forests, woodlands, and scrub biome.
Holodiscus discolor, commonly known as ocean spray or oceanspray, creambush, or ironwood, is a shrub of western North America.
Frangula californica is a species of flowering plant in the buckthorn family native to western North America. It produces edible fruits and seeds. It is commonly known as California coffeeberry and California buckthorn.
Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance; the other type being irritant contact dermatitis (ICD).
Toxicodendron rydbergii, the western poison ivy or northern poison oak, is a species of Toxicodendron in the cashew family native to North America.
Toxicodendron pubescens, commonly known as Atlantic poison oak, or eastern poison oak, is an upright shrub which can cause contact dermatitis for most people.
Toxicodendron vernicifluum, also known by the common name Chinese lacquer tree, is an Asian tree species of genus Toxicodendron native to China and the Indian subcontinent, and cultivated in regions of China, Japan and Korea. Other common names include Japanese lacquer tree, Japanese sumac, and varnish tree. The trees are cultivated and tapped for their toxic sap, which is used as a highly durable lacquer to make Chinese, Japanese, and Korean lacquerware.
Tecnu is an over-the-counter skin cleanser manufactured by Tec Laboratories, a pharmaceutical company based in Albany, Oregon. It is intended for use by humans and furry pets after topical exposure to urushiol, the active ingredient in poison oak, poison ivy, and poison sumac. Tecnu is made from deodorized mineral spirits, water, propylene glycol, octylphenoxy-polythoxethanol, mixed fatty acid soap, and fragrance.
Lithraea caustica is a species of flowering plants in the soapberry family Anacardiaceae. This plant is endemic to central Chile; an example occurrence is in the area of La Campana National Park and Cerro La Campana. The tree is a well known human allergen and can cause a rash of the skin, the effects of and susceptibility to which can vary greatly among individuals.
The California coastal sage and chaparral is a Mediterranean forests, woodlands, and scrub ecoregion, defined by the World Wildlife Fund, located in southwestern California and northwestern Baja California (Mexico). It is part of the larger California chaparral and woodlands ecoregion. The ecoregion corresponds to the USDA Southern California ecoregion section 261B, and to the EPA Southern California/Northern Baja Coast ecoregion 8.
Rhus aromatica, the fragrant sumac, is a deciduous shrub in the family Anacardiaceae native to North America. It is found in southern Canada and nearly all of the lower 48 states except peninsular Florida.
Poison ivy is a type of allergenic plant in the genus Toxicodendron native to Asia and North America. Formerly considered a single species, Toxicodendron radicans, poison ivies are now generally treated as a complex of three separate species: Toxicodendron radicans, Toxicodendron rydbergii, and Toxicodendron orientale. They are well known for causing urushiol-induced contact dermatitis, an itchy, irritating, and sometimes painful rash, in most people who touch them. The rash is caused by urushiol, a clear liquid compound in the plant's sap. They are variable in appearance and habit, and despite its common name, it is not a "true" ivy (Hedera), but rather a member of the cashew and pistachio family (Anacardiaceae). T. radicans is commonly eaten by many animals, and the seeds are consumed by birds, but poison ivy is most often thought of as an unwelcome weed.
Toxicodendron orientale is an allergenic East Asian flowering plant in the genus Toxicodendron. The species was first characterized and named by Edward Lee Greene in 1905. T. orientale is known to grow in Sakhalin, Japan, Taiwan, South central China, and South Korea. It was introduced to parts of Uzbekistan.
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